I have an embarrassing admission to make; up until a few years ago, I thought I knew all there was to know about diagnosing and replacing universal joints (u-joint), I was very wrong. I had been mentored by older technicians 40 years ago when I was the young impressionable new guy in the shop, and I assumed that they knew what they were doing. Over the years, I diagnosed and replaced u-joints in the same manner. Most of the time I thought I was successful, but there were times when I knew something was not right with my installation, but I did not know why.

A few years ago, while preparing for a manual drivetrain class which I teach, I began researching the proper method of diagnosing, removing, and installing u-joints. I found that some manufacturer’s service diagnostic and replacement information was very limited while other manufacturers (including manufacturers of u-joints) give you detailed step-by-step service instructions including specific tools to use and measurements to take. Measurements? What measurements?

I had never been taught about centering a u-joint in the driveshaft yoke ears. I had never been taught to measure and adjust the axial end play of the u-joint with selective color-coded snap rings. I had never seen a u-joint with selective snap rings. After a little more research, I found out that aftermarket u-joints do not come with selective snap rings! I had always purchased aftermarket u-joints. As it turns out, all u-joints are not equal. In this article, we will look at the potential differences in u-joints and how they can impact you and your customer.

Figure 1 – 2017 RAM 2500 Factory U-Joints come with green and blue selective snap rings

I have a few questions to get you thinking about u-joints. We will answer each question in this article.

1. What is the difference between a new $8.99 u-joint and a new $135.00 u-joint kit for the exact same vehicle application?
2. Have you ever installed a new u-joint and had the customer complain of a vehicle vibration afterward?
3. Why do the original factory-installed u-joints in vehicles seem to last forever?
4. Why are a large majority of factory installed u-joints the “sealed” type without a grease fitting?
5. Why are there colored snap rings on many of the factory-installed u-joints?

Warning! Historical Content

Before we discuss u-joints, we need to clarify a little history and terminology. First, it is unknown who invented the original 2-axis u-joint or whatever it was called, but it happened sometime in antiquity (thousands of years ago). Although today the name “Universal Joint” is defined by the Society of Automotive Engineers (SAE) in standard J901, here are the three most commonly used names for u-joints in service information, parts stores, etc.:

1. The Cardan Joint - Incorrectly named in honor of Italian mathematician Hieronymus Cardano (1501-1576) who is credited with describing/inventing a swiveling gimbal with three degrees of freedom (for holding a ship’s compass level in the ocean waves) in 1557. A gimbal is not a u-joint and functions quite differently.
2. The Hooke’s Joint - Correctly named in honor of English mathematician Robert E. Hooke (1635-1703) who in 1675 demonstrated that an angled shaft connected to a u-joint with two degrees of freedom does not rotate at a constant velocity. Hooke also discovered and demonstrated that connecting two u-joints together causes an angled shaft connected to them to rotate at a constant velocity. Today, this constant velocity joint configuration is incorrectly called a “Double Cardan Joint.” Hooke used his inventions in an attempt to display the time of day from a sundial onto a vertical wall so people passing by could easily see the time of day.
3. The “Polhem Knot” Joint - Incorrectly named after Swedish inventor Christopher Polhem (1661-1751) who, after visiting England and studying Robert Hooke’s work, went back to Sweden in 1697 and "Re-invented" the u-joint under his name.

Prior to the rise in popularity of the horseless carriage (automotive industry) in the late 1800s, u-joints were primarily used in industrial applications to connect two machines together. These early u-joints required constant maintenance, cleaning, and lubrication.

in 1902, Clarence W. Spicer (1875-1939), engineer and inventor, invented an enclosure for u-joints to protect them and make them self-lubricating. He obtained 40 U.S. patents between 1903 and 1934 for various designs of improved u-joints and driveshafts. His inventions led to the replacement of the chain-driven axle with shaft-driven axles at the dawn of the automotive industry.

In 1919, Charles A. Dana (1881-1975), businessman, partnered with Spicer, purchased a controlling interest in the Spicer Manufacturing Company and managed the company while Spicer continued innovating and improving u-joints and driveshafts. Dana managed Spicer Manufacturing for 30 years.

in 1946, in honor of Charles Dana, Spicer’s company was renamed to Dana Corporation which has continued to innovate and produce top quality u-joints and drivelines under the “Spicer Drivetrain Products” brand. Spicer is still a major supplier of factory-installed u-joints and driveshafts.

IMPORTANT: In 1982, the Spicer Driveshaft Division of Dana Corporation developed the first all-aluminum driveshaft. Today’s aluminum driveshafts require special Zinc-Phosphate coated steel bearing caps and snap rings in order to avoid severe corrosion caused by electrolysis.

Figure 2 - Spicer U-joint Boxes from 1933, 1957, and 2019

Today there are several aftermarket companies which are in competition with Spicer including many producing lower quality counterfeit/knock-off parts at greatly discounted prices. The use of aftermarket u-joints may cause additional challenges and troubles of which you may be unaware.

The Difference Between Universal Joints

As part of the u-joint research for my classes, I tested six different brands of aftermarket u-joints, two Original Equipment Manufacturer (OEM) u-joints, and two Spicer u-joints for the same application. These u-joints cost anywhere between $8.99 and $135.00 each. I tested each u-joint for the following characteristics:

• Weight of the complete u-joint with snap rings. Always replace both (all) u-joints as a set on the same driveline to maintain balance and reduce moments of inertia.
• The materials from which the u-joint was constructed
• The cross-span variation of the trunnion cross
• The cross-span variation of the trunnion cross with bearing caps
• The bearing cap diameter
• The design of the grease seal(s)
• The recommended bearing lubrication type
• Lubrication service intervals for u-joints with grease fittings
• Lubrication reservoir precautions for sealed u-joints
• Method of reduction of metal-on-metal friction from trunnion thrust surface to bearing cap
• Method of reduction of metal-on-metal friction from needle bearing ends to bearing cap
• Method of needle bearing retention
• Methods of corrosion protection
• The thickness of snap ring set(s)

Both $135 OEM u-joint kits contained a Spicer u-joint kit inside the box. The $35.00 Spicer u-joint kits contained the exact same instruction sheet and part numbers as the OEM kits.

All six brands of aftermarket u-joints were almost identical in appearance, but some had some serious quality and precision issues. To illustrate these issues, let’s look at the answer to the first question at the start of this article: What is the difference between a new $8.99 u-joint and a new $31.99 (or higher priced) u-joint for the exact same vehicle application?

The $8.99 universal joint– The graphic in figure 4 depicts an $8.99 u-joint available today online and in many auto parts stores. At first glance, you may not realize that you are actually looking at technology from a 1968 Dana patent (US3369378A) that expired in 1985. When a patent expires, the technology is open for the rest of the world to use. It appears that many suppliers of aftermarket u-joints simply copy the technology from old, outdated, expired patents and hope that the general consumer will not know any different. In reality, today’s modern u-joints can outlast this old technology by a factor of 10 to 1.

Figure 3 - 51-year-old technology from expired patents

Quality Control? - Five out of the six aftermarket u-joints I tested had less than impressive quality controls regarding precision machine work. Some were worse than others. The worst can be seen in figure 4. The cross-span variation measurement across the two sets of opposing bearing caps was 0.180mm (0.007”). By comparison, the same measurement on the OEM and Spicer u-joints was 0.025mm (0.001”). Any cross-span variation can result in an offset u-joint cross centerline. An offset u-joint cross and the resulting offset driveshaft can cause a vibration if the driveshaft runout was already on the borderline of specifications. In other words, installing this u-joint could cause a vibration. This is one of the answers to question 2 at the start of this article.

Figure 4 - Lack of precision resulted in a cross-span variation of 0.007" (0.18mm)

The typical contents of an aftermarket u-joint kit can be seen in figure 5. This 51-year-old design has several disadvantages when compared to a modern Spicer design.

Single Flexible Rubber Seal– This design of grease seal does a poor job of keeping the grease inside the bearing caps. It also does a poor job of keeping dust and moisture out of the bearing caps. Because this seal does such a poor job, periodic flushing of the old grease, dust, and moisture with new grease is required to maintain bearing life. This explains the need for a grease fitting.

Grease fitting– I used to think a u-joint with a grease fitting was a good thing, but I no longer think that way. The problem with using a u-joint with a grease fitting is remembering to have it greased properly (the flushing process). I personally have been to national chain stores for an oil change in my own vehicle. When they were finished servicing my vehicle, I asked them how many grease fittings they lubricated; they told me my vehicle had sealed joints and no lubrication was necessary. I knew it had several grease fittings and I had to tell them where they were. I am sure they hated having me for a customer.

Snap Rings– All six aftermarket u-joint kits I tested came with one set (4) of snap rings. The thickness of the snap rings averaged 1.37mm (0.054”). The average typical snap ring thickness used with Spicer u-joints is 1.50mm (0.059”). One benefit to using snap rings which are too thin is they fit into the snap ring groove easier than thicker snap rings do.

Replacing the original snap rings with these thinner snap rings would result in an increase in the driveshaft runout of 0.13mm (0.005”) because of the additional axial end play in the u-joint assembly. This condition will cause the driveshaft to orbit rather than rotate on a centerline. This additional runout can cause a driveshaft vibration. This is also one of the answers to question 2 at the start of this article.

Now, imagine the vibration caused by the wrong combination of an offset u-joint cross and these snap rings. The worst-case scenario with this u-joint could have an additional 0.30mm (0.012”) of driveshaft runout just from changing a single u-joint! Many driveshafts have a maximum runout specification of 0.51mm (0.020”). Almost all driveshafts I have tested for runout measured at least half of their specification, even on brand new vehicles. It would not take much more runout to exceed the maximum allowed.

Friction Producing Design– All six aftermarket u-joints I tested were designed with the thrust end of the trunnion cross rubbing metal-to-metal on the bottom of an unmachined bearing cup. Additionally, the bottom of the needle bearings makes metal-to-metal contact with the bottom of an unmachined bearing cup.

Misleading Advertising/Markings– One of the six aftermarket u-joints I tested came from a major auto parts chain here in the U.S.A. “Made in China” was printed on the outside of the box, yet the letters “USA” were cast into the u-joint cross. It makes me wonder if this is a knock-off u-joint.

Figure 5 - Typical Aftermarket U-Joint Kit Contents

The $35.00 to $135.00 Universal Joint– The patented technology used in OEM and Spicer u-joints allows them to last ten times longer than the $8.99 u-joint. Let’s look at this technology.

Triple Lip Seal Design– As shown in figure 6, the inside lip seal faces the bearing cap and keeps the grease inside the bearing caps and lubrication reservoir. The other two lips are facing the trunnion cross and keep dust and moisture out of the bearings. Because this seal does such a good job, no external grease fitting is required for grease flushing and bearing life is extended. This answers questions 3 and 4 at the start of this article.

Seal Guard– The seal guard protects the triple lip seal from damage from mud or road debris as you drive. The seal guard is an important improvement in u-joint design.

Figure 6 - Patented triple lip seal design

Quality Control - The two OEM and the two Spicer u-joints I tested had impressive quality controls regarding precision machine work. As can be seen in figure 7, the cross-span variation measurement across the two sets of opposing bearing caps was a consistent 0.025mm (0.001”) or less.

Figure 7 - Very low cross-span variation

Corrosion Protection– As mentioned before, aluminum driveshafts require special Zinc-Phosphate coated steel bearing caps and snap rings in order to avoid severe corrosion caused by electrolysis. OEM and Spicer u-joints may have just two of the bearing caps coated with zinc-phosphate (dark brown/grey coating). Those two bearing caps are to be installed into the aluminum yoke ears of the driveshaft; the steel bearing caps are to be installed into the steel companion yoke ears. When replacing a u-joint in an aluminum driveshaft, be sure to use the coated bearing caps and coated selective snap rings.

Thrust spacer– These kits were designed with a nylon spacer on the thrust end of the trunnion cross to prevent metal-to-metal friction with the bottom of the machined bearing cap.

Thrust Washer– These kits were designed with a nylon thrust washer installed between the bottom of the needle bearings and the bottom of the bearing cup. The purpose of the thrust washer is to prevent metal-to-metal friction.

Figure 8 - Typical OEM and Spicer U-Joint Kit Contents

Snap Ring Sets – The OEM and Spicer u-joint kits contain three sets of (4) color-coded selective snap rings. U-joint kits for aluminum driveshafts also contain three sets of selective snap rings, but they are not color-coded since they are coated with zinc-phosphate.

There are two reasons for using selective snap rings (from question 5 at the start of this article):

1. As seen in figure 9, the snap rings are used to adjust the axial end play in the u-joint. Axial end play is the space between the trunnion thrust surface and the bottom of the bearing cap and is measured with a dial indicator. Axial end play is adjusted by changing to a thicker or thinner snap ring on each side of the same u-joint cross.
   1. Too little end play can lead to premature u-joint failure due to friction and lubrication blockage.
   2. Too much end play can contribute to excessive driveshaft run out and cause a vibration
2. The snap rings are also used to center the u-joint cross in between the yoke ears of the driveshaft. You must use the same thickness of snap ring on each side of the same cross to keep the u-joint centered in between the driveshaft yoke ears. Always measure each snap ring and keep track of where you install it.

Snap rings are easily damaged and should not be reused if they do not spring back to their original dimensions (compare to a new snap ring)

Figure 9 - How to measure and adjust axial end play

Summary

Hopefully, you have learned enough to know what to look for, and what look out for, when purchasing and servicing u-joints. As for me, I will always use the better quality, more expensive Spicer u-joints in any vehicle of mine. Best wishes!

Article Details

Tue, 10/01/2019 (All day)

John D. Kelly

<p>There&#39;s very little &quot;universal&quot; about universal joints and their service. Learn the right way to troubleshoot and service these important driveline components.</p>

<p>Universal joint, u-joint, auto repair, service, driveline</p>

TBC Brands, one of the largest distributors of private brand tires in North America, is adding eight new sizes to its agricultural tire line, Harvest King Field Pro I-1 Implement, and two sizes to the skid steer line-up, Power King Rim Guard HD+.
 
All sizes of the Field Pro I-1 Implement are available in tubeless construction and the enhanced tread compound provides improved resistance to stubble damage.  The Power King Rim Guard HD+ features an extra deep tread with sidewall protection for outstanding cut and chip resistance and durability.
 
“TBC Brands is excited to add additional sizes to these popular lines,” said Bill Dashiell, SVP of the Commercial Tire Division for TBC Brands. “The expansion of product sizes allow us to meet our customers’ needs with high quality products. The new sizes are targeted for customers who want easy steering on agricultural implements and excellent durability for heavy-duty construction service.”   
 
The eight new Harvest King Field Pro I-1 Implement sizes are:
5.90-15 B
6.70-15 C
11L-16 D
12.5L-16 F
9.5L-14
11L-14
14L-16.1 available October 2019
16.5L-16.1 available October 2019
 
The two new Power King Rim Guard HD+ sizes are:
31X15.50-15 E
31X13-16.5 E
 
Harvest King agricultural tires and Power King off-highway tires both feature a five-year warranty for workmanship and materials that includes a no charge replacement within the first twelve months with 10% or less of the original tread depth used if it becomes unserviceable due to a defect in design, workmanship, or material.  A prorated allowance is available after the no-charge replacement period or the tread use exceeds that allowed based on the date of manufacture and the amount of tire use after it was installed.
 

Article Details

Mon, 09/30/2019 (All day)

MOTOR AGE Wire Reports

<p>TBC Brands, one of the largest distributors of private brand tires in North America, is adding eight new sizes to its agricultural tire line, Harvest King Field Pro I-1 Implement, and two sizes to the skid steer line-up, Power King Rim Guard HD+.<br />&nbsp;</p>

<p>TBC brands, tires</p>

A technician from Zimbabwe epitomizes what it means to be committed to your profession. His story is so motivating I asked him to share it, in his own words, with all of you.

My name is Taurayi Raymond Sewera. I grew up in a family of four boys and one girl living in the high-density suburb of Glen Norah in Harare, Zimbabwe, Africa.

I had a very tough life growing up where I could barely get three meals a day. My mother would sell hand-sewn clothes she made to take care of our family while my father barely took care of our family most of my childhood life. He became more involved in our lives when I was 13 years old and passed on when I was 19. I became the bread winner for my family at the age of 20 and I started working on cars as the best way to provide for them. I am a self-taught automotive technician.

I would work on anything automotive that presented itself to me from light gasoline, light diesel and even heavy-duty diesel vehicles including earthmoving equipment. I started my career selling vehicle spares — mostly used ones that I got from salvage yards. In the early part of my career, I was working in and out of a highly informal industrial place called Gazaland in the Highfield suburb.

I have over a thousand automotive books in my personal library and study them nearly every night in my quest to become one of the world's best.

At the age of 22, I got married to my beautiful wife, Faith. Two years later we had our first child, Chantell. Together, my wife and I have had five children. My growing family added additional responsibilities on my life as the family bread winner and it pushed me to work even harder.

Unfortunately, we tragically lost our second-born child, Russell (nicknamed ‘Russy Dollar’ by my best childhood friend). The passing on of my child devasted my wife and I, and even up to this day it feels like we lost him only a year ago. I became an alcoholic after the passing on of my son and remained so until 2015 when I finally decided to quit drinking alcohol. And even though I'm sober, I pay the price still today. Beer has already extremely damaged my pancreas and I am now suffering from chronic pancreatitis.

What has truly turned my life around was the decision to become a Born-Again Christian, and from that day I have never looked back. I made a prayer to the Almighty telling him how much I wanted to turn my life around and become one of the best automotive technicians in the world.

My quest to become one of the best took off in 2016 as I was watching a YouTube video of an American automotive instructor by the name of Jim Morton. The video was Mr. Morton teaching an ignition waveform diagnostics class at a TST (Technicians Service Training) event. At the beginning of the class, Jim wrote his email address on the board and I chanced emailing him, telling him of my desire. Fortunately enough, Jim replied my email and told me how he was impressed by my desire.

Jim told me that in order to become one of the best, I needed to attend one of the best automotive training events in the world — like the VISION Hi-tech Training event held every March in Overland Park, Kan. He also mentioned how unfortunate it was that I lived so far away because of the costs involved and what it would take for one to attend this event all the way from Africa.

Not to be discouraged, I told Jim I was 100 percent dedicated to automotive technology training and I was willing to pay for all the costs to attend this legendary event. Jim managed to link me up with Sheri Hamilton, the Executive Director for VISION. Sheri was very happy to help and provided me with all the necessary paperwork to facilitate my USA Visa so that I could attend VISION.

I became the first and only African to ever attend VISION in 2017. And I've attended every year since. While I was at the 2017 VISION Hi-Tech training event, I received an award for the furthest travel ever by a VISION attendee. But the award is nothing compared to my experience in attending. I cannot thank Jim and Sheri enough. It has changed my life and my ideas of what being the best really means. It has provided me with the opportunity to attend classes from the world’s greatest instructors like John Thornton, Bernie Thompson, Scot Manna, G “Jerry” Truglia, the late Harvey Chan, Scott Shotton, Matt Fanslow and many more I don't have the room to mention. I was also fortunate enough to meet great techs from around the United States and others from countries around the world. Attending VISION really impressed on me how much technology is changing in the automotive industry and the need to receive as much training as possible every year. Most of the training available at events like VISION, the TST "Big Event," "Super Saturday" and many more cannot be found in text books. It is the latest information and techniques that are developed by these great instructors and technicians, earned as they work on cars every day.

If not for the support and mentorship of my great friend, Jim Morton (r), I may never have discovered the opportunities events like VISION have to offer.

There is no substitute to these "live" automotive training classes. If one wants to be the best one can ever be, one ought to attend these training events. I believe the training offered at these events does not cost, but pays. Ever since I started attending training events like VISION, I learned that I cannot afford to miss it even though I travel over 9,000 miles one way to the USA.

It is the best decision I have ever made in my 21-year career as an automotive technician. I have also decided to take ASE exams every time I travel to the USA. I have managed to take all nine automotive certifications offered to become an ASE Master Automobile Technician. I have also managed to pass ASE Advanced Level Specialist in Engine Performance (L1), Medium Electronic Diesel (L2), Hybrid and Electric vehicles (L3), Undercar Specialist (X1), and I am also currently ASE certified in five systems related to medium and heavy-duty trucks.

At the time of writing this, I am about to travel to Massachusetts for a hybrid and electric vehicles internship with ACDC, owned by Craig VanBatenburg. While I am there, I will be taking additional ASE tests including three systems in medium and heavy-duty trucks to become a Master Technician in that category. I am also going to take 16 more ASE tests to become ASE Master Technician in Truck Equipment, Collision Repair/Refinish and Transit Bus. I am currently left with only seven ASE systems to be recognised as an ASE World Class Technician!

 It seems to me that, with so many great training events held every year in the USA, most American technicians take training for granted. I hope you will gain inspiration through my journey as an automotive technician. I believe there is no appropriate excuse for not going to these training events. I also hope you appreciate how fortunate you are to be exposed to these extraordinary training events.

I also urge you to go and take ASE tests in support of this incredible accreditation. After all, it's all we have to highlight our efforts to be total professionals. If only you could imagine what it's like to travel to the USA or Canada just to take these tests. I come from Zimbabwe, which is one of the poorest countries in the world but still manage to save my hard-earned money to travel to America for both training and ASE tests.  

To me, training is very personal. I take it to heart. There is nothing I love more than training and to have all the knowledge to work on the latest technology vehicles including hybrid and electric vehicles. I am by no means wealthy — it is all in pursuit of knowledge. I just want to be a better technician every day and will do anything to save money and find the time to attend these phenomenal training events.

I have more than a thousand automotive-related training books in my collection. I got most of them from auto tech friends I met when I attend training events in the States. In addition to attending the training events, I study these books from 11 p.m. to 2 a.m. almost every single day. All to hopefully one day realize my dream of becoming one of the world's greatest techs!

Article Details

Mon, 10/28/2019 (All day)

Pete Meier

<p>A technician from Zimbabwe epitomizes what it means to be committed to your profession. His story is so motivating I asked him to share it, in his own words, with all of you.</p>

<p>Taurayi Raymond Sewera, technician, Zimbabwe, training, VISION,</p>

There are over 8 million trucks and SUVs produced each year in North America. If 50 percent of those vehicles are four-wheel-drive or all-wheel-drive, a total of 12 million axle assemblies are needed to supply those vehicles. Twelve million axles per year equal 32,876 per day, or 1,370 per hour, or 22.83 axles per minute. What are the chances that every axle is set up correctly? The chances are pretty low. I tell my students, “Just because it is new, does not mean it is set up correctly.”

Over the years, I have received many questions related to what has become known as “Chevy Shake” vibrations on later model Chevrolet, GMC, and Cadillac trucks and SUVs. Similar vibrations have occurred on the Ford Mustang the Ford F-150, and Ram 1500 and 2500 trucks. The frustrating thing for the customer is that nobody can diagnose and repair them, or even worse, they are told it is normal.

A tale of two trucks
I have been personally involved in diagnosing two vehicles that were purchased back from the customers for unresolved vibration problems. The first vehicle is a $90k 2015 Cadillac Escalade 4x4 SUV. The second is a $55k 2014 GMC Denali 1500 Series 4x4 Crew Cab short-bed pickup truck. Both of these vehicles had the exact same cause of the vibration; a rear axle that was not set up correctly.

Figure 1 - Measuring total turning preload on a rear axle

2015 Cadillac Escalade 4x4 SUV
In the spring of 2016, I was teaching a manual drivetrain class at the university where I work. As part of that class, we always go through the complete inspection, disassembly, repair and assembly process of a rear axle. We had three vehicles on the hoists and five axles on the workbenches. I love to work on vehicles with real problems, so I gathered my students around the 2015 Cadillac Escalade 4X4 on the hoist and told them about the vibration problem that resulted in the buyback of this vehicle. I told them we would carefully inspect the 9.75” rear axle as we disassembled it to see if the rear axle had any troubles that may have contributed to the vibration.

Following the same diagnostic procedure I have taught for years, one of the very first steps you should perform when diagnosing and disassembling a rear axle is to measure what is known as the “Total Turning Preload” of all the preloaded bearings that hold the ring and pinion gearset in place inside the axle housing. This measurement should be done at the pinion nut with the driveshaft, wheels, and tires, and brake rotors removed. Using a flexible beam type or dial-type inch-pound torque wrench, a technician should rotate the pinion nut and see what the constant rotational torque (effort) is. Typically, the measurement is at least 1.7 - 2.8 Nm (15 - 25 in*lbf) on an axle that is set up correctly, and we measured zero! I could not believe it! The only time I had ever read anything close to 0 Nm (0 in*lbf) of rotational torque was on a 35-year-old severely worn axle with high mileage on it. This axle is in a one-year-old Cadillac; how could this be?

Figure 2 - The 2015 Cadillac Escalade with an “unfixable” vibration

2014 GMC Denali 1500 Series 4x4 Crew Cab short-bed pickup truck
Next, we moved to the 2014 GMC Denali 1500 Series 4X4 Crew Cab short-bed pickup truck and performed the same measurements. It also read 0 Nm (0 in*lbf) of rotational torque for the “Total Turning Preload” measurement. The truck had the same rear axle housing except is had a 9.5” ring gear rather than the 9.75” ring gear in the Cadillac. Having two vehicles with zero bearing preload is unheard of; there must have been a problem with the axle setup, the lubricant, or something was very wrong here from the factory. My suspicions in 2016 were confirmed earlier this year (2019) when a friend of mine, who is also a GM Field Service Engineer, confirmed that “many of the axles out of an assembly plant in Mexico had problems.”

There is no excuse to have an improper setup axle on a new vehicle anymore. Axles have been mass-produced for over 100 years now. Sure, there have been improvements in materials and machining, but the same setup process has been in use all of that time. A properly set up axle is silent under all operating conditions and temperatures; it outlasts the lifespan of the rest of the vehicle.

Causes of axle vibrations and noises

Improper Bearing Preloading — Proper bearing preload on the ring and pinion gear set prevents the gears from moving vertically, horizontally, or diagonally as they rotate. Improper bearing preloading allows the gears to push away from each other as you accelerate your vehicle and pull together as your vehicle decelerates. Any gear movement can cause the gear backlash to become too small and have the gears bind with each other as they try to rotate. These conditions cause noises, vibrations and oil leaks.

• The ring gear rotates at tire speed and can mimic a tire speed-related vibration. 
• The pinion gear rotates at driveshaft speed and can mimic a driveshaft speed-related vibration.
• Improper pinion bearing preload can cause what appears to be a pinion seal leak, but the seal is fine, the pinion gear is moving vertically, horizontally, or diagonally as is rotates. No seal can hold on oil under those conditions.

Figure 3 - Differential case side bearing preload

Improper Gear Tooth Contact Pattern — A properly set up axle utilizes the entire length of each gear tooth to transfer all the torque from the engine/transmission to the axles/wheels. A gear tooth contact pattern check will reveal if the proper contact is being made. If improper tooth contact is made, only part of the gear tooth is transferring all the torque from the engine to the wheels. This can cause noises, uneven tooth loads, and contribute to broken gear teeth and catastrophic axle failure. Improper bearing preloads can contribute to these conditions.

• An axle noise that only occurs on acceleration is an indication of improper gear tooth contact on the drive side of the ring gear teeth. 
• An axle noise that only occurs on deceleration is an indication of improper gear tooth contact on the coast side of the ring gear teeth.
• An axle noise that occurs on acceleration and deceleration is an indication of improper gear tooth contact on both the drive and coast sides of the ring gear teeth.

Figure 4 - An example gear tooth contact pattern

Diagnostic disassembly steps
Do you want to be able to quickly diagnose axle problems as we did with the two trucks listed above? You should never start unbolting parts and disassembling an axle with noises or vibrations. There are many clues you can find by carefully taking measurements and making observations during disassembly. I have my students use the following steps during axle disassembly in my classes.

1. Measure the Total Turning Preload (TTP) — This measurement should be done at the pinion nut with the driveshaft, wheels, and tires, and brake rotors removed. Using a flexible beam type or dial-type inch-pound torque wrench, rotate the pinion gear at the pinion nut to measure the Constant Rotational Torque (CRT) of the pinion bearings and the differential case side bearings combined. Note: Some axles use the “Break Away Torque (BAT)” rather than the CRT. Typically, the CRT measurement is at least 1.7 - 2.8 Nm (15 - 25 in*lbf) on an axle that is set up correctly. Anything less is an indication of a problem. IMPORTANT: while rotating the pinion gear at the pinion nut, watch and feel for any fluctuations in the rotating effort. Any fluctuations can indicate damaged bearings.
2. Inspect the oil/fluid — Utilizing a drain pan to capture and save the fluid, remove the differential cover and inspect the oil for a burnt odor, for contamination from water/rust/corrosion, for metal flakes (many differential covers have a magnet to attract loose metal flakes). Any problems with the oil/fluid can indicate the need for a complete overhaul of the axle assembly.

Ring gear type – Look at the ring gear to determine if it is a face-milled ring gear (with unequal gear tooth depth), or face-hobbed ring gear (with uniform gear tooth depth). Face milled ring gears are more prone to suffer from backlash variation problems. These two ring gear types also have different gear tooth contact patterns.

Figure 5 - Examples of face milled and face Hobbed ring gears

1. Measure the backlash variation – If the TTP from step one was within specification, measure and record the backlash of every gear tooth on the ring gear, (yes, all 32-48 gear teeth). Any difference between the lowest backlash measurement and the highest backlash measurement greater than 0.051mm (0.002”) indicates a problem. The problem could be with the ring gear itself, or with the differential case to which it is bolted. Further measurements of differential case lateral and radial runout are necessary. Any differential case runout higher than 0.051mm (0.002”) indicates the differential case must be replaced.
2. Measure the Pinion Bearing Preload (PBP) – Important: Mark all parts as left side or right side when removing them. Remove the axle shafts, differential case bearing caps, and the differential case. The differential case should be difficult to remove if it has the proper amount of side bearing preload. You may have to pry on the ring gear bolts to remove the differential case from the differential housing. Using an inch-pound torque wrench, rotate the pinion gear to measure the CRT of the pinion bearings alone. Typically, the CRT measurement is at least 1.1 - 1.7 Nm (10 - 15 in*lbf) on an axle that is set up correctly. Anything less is an indication of a problem.

After making all the measurements and inspections listed above, you will have a good idea of the parts required and how much work is needed to repair the axle. Always replace the bearings when the bearing preload is out of specifications. Notice: Replacement bearings can be thicker or thinner than the original bearings. Because of this, it is very rare that the thickness of the original pinion depth shim(s) and differential case side bearing shims will be correct to use with the new bearings.

Critical reassembly steps
Almost anyone in a wrinkly T-shirt can bolt the axle parts together and send the vehicle down the road; It takes a trained technician with a lot of patience and attention to detail to set up an axle correctly. Proper setup of an axle can take four to eight hours depending upon how lucky you might be.

Before reassembling an axle, clean everything thoroughly. Always use the correct thread locking compound and primer before installing bolts or nuts. Only use the correct axle gear lubricant during reassembly to lubricate bearings and gears.

Use the following steps to assemble properly and set up an axle.

1. Avoid bearing Brinelling – When assembling an axle assembly, do not hit bearings or parts with bearings on them with a hammer or impact wrench; bearing Brinelling (small indentations in the bearing surfaces) can occur. Bearing Brinelling causes fluctuations in the rotating effort of the bearing. Any fluctuations can indicate damaged bearings.
2. Set pinion depth – If you have access to the special tools needed to measure the shim(s) required for the pinion depth, use them. If you do not have access to the tools, use the old pinion depth shim(s), but be mentally prepared to disassemble the entire axle again to change the depth shim if the gear tooth contact indicates the shim thickness is incorrect. Changing the pinion depth shim typically requires replacing the pinion seal, front pinion bearing, and the crush sleeve (if equipped).
3. Set pinion bearing preload — Set the pinion bearing preload at the high end of the specifications. Over time the bearing preload will only loosen, so if you start at the high end of the specifications, it will last longer. There are two methods of setting bearing preload.
   1. Method one uses a crush sleeve and a non-reusable pinion nut. Tighten the nut until the proper PBP is obtained. If the PBP is incorrect, change the crush sleeve, front bearing, seal, and nut and measure the PBP again.
   2. Method two uses pinion preload shims and a non-reusable pinion nut. Tighten the pinion nut to a specific torque and then check the PBP. If the PBP is incorrect, change the preload shims, front bearing, seal, and nut and measure the PBP again.
4. Set the differential side bearing preload - Set the differential side bearing preload at the high end of the specifications. Side bearing preload cannot be directly measured; it can only be calculated. The formula: ((TTP) – (PBP)) x Axle Gear Ratio = Side Bearing Preload. Example: ((30 in*lbf) – (20 in*lbf)) x 3.23 = 32.3 in*lbf. If the Side Bearing Preload is incorrect, change the side bearing shims by an equal amount on the left and the right sides to prevent changes in the ring gear backlash. Some axles use threaded side bearing adjusters rather than shims to set bearing preload and backlash.
5. Set the Ring gear backlash — Set the ring gear backlash at the middle of the specifications. If the backlash is incorrect, adjust the side bearing shims by decreasing the shim thickness on one side by the same amount of the shim thickness increase on the other side. This will maintain the side bearing preload.
6. Run a contact pattern check – Using gear marking compound, paint the drive and coast side of every ring gear tooth, not just three or four teeth. Install the axle shafts and brakes. Partially apply the brakes to load the ring gear to the point that it takes about 50 ft*lbf to rotate the pinion flange. Rotate the flange 3 to 4 rotations forward and backward.
7. Interpret the contact pattern - Make all final adjustments to the axle set up based upon the gear tooth contact pattern results. Always recheck the pattern after adjustments are made. There are five possible patterns if the backlash is within specifications
   

   1)     Centered - The pattern is centered along with the gear teeth on both the coast sides (concave) and drive sides (convex) of the ring gear teeth.

   2)     Toe-Heel – The contact pattern is closer to the toe of the drive side and the heel of the coast side of the ring gear teeth. Move the pinion gear away from the ring gear.

   3)     Heel-Toe – The contact pattern is closer to the heel of the drive side and the toe of the coast side of the ring gear teeth. Move the pinion gear closer to the ring gear.

   4)     Toe-Toe – The contact pattern is closer to the inside of the ring gear teeth (the toe) of both the drive and coast sides of the ring gear teeth. The backlash is too small.
   
   5) Heel-Heel – The contact pattern is closer to the outside of the ring gear teeth (the heel) of both the drive and coast sides of the ring gear teeth. The backlash is too wide

Figure 6 – Proper pinion bearing preload holds the pinion gear from moving while rotating

Figure 7 – Non-Reusable Cast iron shim (left) and a service spacer and shim (right)

Figure 8 - A contact pattern interpretation chart for face Hobbed gears

Summary
Regarding the two trucks at the start of this article. We replaced all the bearings and one ring and pinion gear set and set up the axles correctly upon reassembly. We could not drive the vehicle on the road since they were donation vehicles to my school, but we did test them on the hoists, the vibrations were gone.

There were incorrectly setup/failing parts in these axles, but nobody (including several competent flat-rate technicians and a GM “Field Service Engineer”), detected them. Two unhappy customers were the result. Thousands of dollars were wasted on attempted repairs; many hours of labor were wasted. My students and I diagnosed both of these vehicles in less than 30 minutes by following basic diagnostic steps; you can do the same thing. Best wishes!

Article Details

Fri, 11/01/2019 (All day)

John D. Kelly

<p>Over the years, I have received many questions related to what has become known as &ldquo;Chevy Shake&rdquo; vibrations on later model Chevrolet, GMC, and Cadillac trucks and SUVs.</p>

<p>axle vibration, automotive, noise, Chevy Shake,</p>

Even though the cooling system has a year 'round job to do, it seems that we pay a little more attention to it when the leaves start to turn color and the temperature starts to drop. Not that that has anything to do with the cooling system's role in dispersing excess heat generated by the engine. No, as the mercury starts to drop, our concern is whether or not the coolant is protected from freezing in the block — and that's not a bad starting point for any cooling system inspection!

It's a package deal

The coolant used to protect your customers' engines is similar in all applications in that it is typically a 50/50 mix of water and ethylene (or propylene) glycol.

Why a mix? Water is an excellent medium for removing heat but it provides no protection to the build-up of rust or corrosion in the cooling system passageways or components. It also has a limited operating range, with a freeze point of 32°F and boiling point of 212°F. The development of pressurized cooling systems back during World War II helped raise the upper limit a bit but it did nothing to lower the bottom end, so something had to be added to the water to prevent freeze up. Hence, the glycol.

Ethylene glycol has a freeze point of 10°F and a boiling point of 386°F. The high end is plenty good but the low end is still short on freeze protection when used in extremely cold climates. Alone, it is also less efficient than water at adsorbing heat — about 10 percent to 20 percent less efficient. So, while it appears a better choice than pure water alone (and it is), the use of coolant alone is still lacking and no better as an option.

However, when mixed in a 50/50 proportion, the resulting cooling fluid has a freeze point of -34°F and, with a 14 psi radiator cap installed, a boiling point of 265°F. According to most of the manufacturers’ I spoke with, a working mixture range of 40 percent to 60 percent will still provide sufficient heat transfer while maintaining freeze protection.

What's the best way to test the mixture ratio? Manufacturers agree that the use of a refractometer is the best way to test with coolant test strips coming in a close second. They also agree that the hydrometers of old are not accurate enough to test the coolant mixture and should be avoided.

The best way to check the mixture ratio is with a tool called a refractometer. Just be sure to compensate as outlined in the tool's manual prior to taking your reading.

Still serviceable

If the mix ratio is ok, does that mean the coolant is still serviceable?

We still haven't done anything to protect the cooling system internals from the effects of the water passing through them. An additional chemical package is added to the cooling fluid to protect components and passages from the effects of oxidation and corrosion. This package is called the "inhibitor package" and is generally designed to keep the coolant mixture a tad on the alkaline side, rather than the acidic side. There are three basic types of coolant mixtures; Inorganic Acid Technology (IAT), Organic Acid Technology (OAT) and Hybrid Organic Acid Technology (HOAT). OEMS may require tweaks on the inhibitors for their own models and that's one reason there are so many different combinations and colors on the market.

Now, I don't care if you know an IAT from an OAT or an HOAT. What I do care about is that you understand that these inhibitor packages don't last forever. As they "drop out" or are used up, the coolant becomes more acidic. This leads to leaks in the heat exchangers, damage to the water pump impeller, and erosion of the passageways to the point of internal coolant loss.

What causes the inhibitor package to be consumed? Aging of the coolant is one and that's the reason for the service interval you see in the maintenance schedule. But other factors can speed up the process and if left unchecked or undiagnosed, allow cooling system damage to begin long before that interval arrives. For example, contamination of the coolant (by internal fluid leaks or combustion chamber gasses mixing with the coolant) is more common than you think. One resource I spoke with estimates that nearly half of the vehicles on the road today have leaking head gaskets that can shorten the life of the coolant yet not pose any drivability issues for the consumer other than having to top off the recovery bottle every now and then.

Another common cause of premature loss of the inhibitors is a bad engine-to-chassis electrical ground. Bad ground(s) can encourage current to find its way back to the battery through the cooling fluid and that results in a rapid consumption of the inhibitors.

How do you test the condition of the inhibitor package? Coolant test strips typically include a section that will react to the pH level of the coolant. This is probably the easiest and most accurate way to test outside of having a lab analyze a sample.

Test strips are fast and accurate ways to test coolant. Both mixture ratio and the essential pH check can be done in minutes.

Many of you may remember using a voltmeter to measure for the presence of stray voltage in the coolant. The process is simple enough. Attach the ground lead of your meter to the negative battery post and then insert the positive meter probe into the coolant, avoiding contact with the metal in the radiator. If the inhibitor package has been depleted and the cooling fluid has become acidic, the fluid will react with the metals in the cooling system similar to the way sulfuric acid reacts with the lead plates in the battery. It is called a "galvanic" reaction and produces a voltage potential you'll see on your meter face. Anything more than 0.30 to 0.50 volts is indicative of a problem.

A word of caution here, though. The presence of voltage on your meter does not necessarily provide conclusive evidence that it's the acidity level of the coolant that's causing the problem. You may be measuring the effects of that bad ground I mentioned earlier.

This old school test looks for the presence of stray voltage in the coolant. The catch is which came first; the stray voltage (caused by a bad ground) or the acidic coolant (resulting in a galvanic reaction)?

Both are bad news and both need to be isolated and corrected. The question you have to answer, through testing, is did the acidity level of the coolant become excessive on its own or is there a bad electrical ground allowing the inhibitor killing current in.

Your inspection process

The first step I want you to take is to review the cooling system description for the vehicle you are servicing in your service information system. Many vehicles today use multiple coolant paths — heck, even multiple water pumps and thermostats!

Next, perform a thorough visual inspection. How much coolant is in the recovery bottle? Coolant doesn't just evaporate — if the level is low there's a reason for it. Be sure to ask your customer, too, if they have had to add coolant with any regularity.

If there is any reason to suspect a leak, look for any visual signs of that next. These can be tough to see, especially if the leak is small. Pay special attention to the area where the plastic side tanks are attached to the radiator's heat exchanger. There is a gasket in there that allows for the thermal cycling of the components and that ages over time. The crimps holding the parts together can only be made so tight and small leaks here are common.

This leak is the result of poor maintenance. The coolant inhibitors were used up and corrosion began to set in, eventually eating through the radiator's tubing.

Dye technology has come a long way and the addition of the proper dose of dye may make that leak a lot easier to locate. Just remember a few "best practices". Use the dye maker's specified dosage in the system — no more and no less. Use the UV light that came with the dye kit. It makes a difference as dyes fluoresce differently under different UV wavelengths. And use the yellow glasses to make the dye even more visible. It won't hurt to darken your work area a bit, either.

Don't forget to inspect the belts and hoses while you're at it. Since nearly every accessory drive belt today is a serpentine design made with EPDM and can be worn out well before you see any visual indications, you’ll need a belt wear gauge to perform this check. As for the hoses, the biggest cause of cooling system hose wear is electrochemical degradation, or ECG, and it’s not easy to detect. ECD attacks the rubber from within and is caused by the same acidity developed in the coolant we just talked about.

Check the hoses by squeezing them between your thumb and forefinger. The hoses should feel soft and pliable. If they feel tight or crunchy, they may require replacement. Take a close look at the hose connections, looking for signs of softness, bulging (especially when the system is under pressure), or cracks that could be signs of damage caused by ECD or age. Even if the hose appears to be ok, a good rule of thumb is to recommend hose replacement when a hose is over five years old.

Pressure test the system to make sure it can hold the pressure it’s supposed to, and don't forget the cap. Weak caps resulting in lower boiling points can allow the water in the coolant to vaporize, creating air in the system. It can also prevent the normal siphoning of the coolant from radiator to recovery bottle and back again.

Leaking head gaskets are common as well, with some resources estimating that 50% of the cars on the road suffer from at least a minor one. And that's all it takes to impact the longevity of the coolant.

Of course, using your refractometer and/or test strip, test the percentage mixture and pH level. If the pH level is ok, the percentage mixture can be adjusted by adding pure coolant or deionized water as needed, but if the pH is out of whack only a thorough flush and refill will do the trick.

A word on water

You may have noticed that there are more and more pre-mixed coolants on the store shelves than there used to be. The reason is simple enough. Water is half the equation and cooling systems are not very tolerant of water that is contaminated before it is even poured into the radiator.

I encourage you to use these pre-mixed solutions to avoid complications caused by bad water. Even the best tap water is aerated to improve the taste and using aerated water is a bad enough idea all by itself. Why would you want to add air to the cooling system right off of the bat?

Not too long ago, I got my hands on a testing tool called a "precipitator." This device passes an electrical current through the water sample and causes any solids in suspension to drop out and become visible. The results were eye-opening! If you must make up your own mixture, use deionized water (first choice) or distilled water (second choice) to not only fill the system but also to flush the system to avoid leaving contaminants behind.

What about universal coolants?

According to an article on the Automotive Aftermarket Suppliers Association (AASA) web site, " Universal coolants typically use a proprietary OAT formula that may or may not contain silicates (to meet the GM requirements), and no phosphates or borates (to meet European and Japanese requirements). Universal coolants can be mixed with ANY type of coolant, including the older traditional green formula coolants, and can be used to refill almost ANY year/make or model of passenger car or light truck. We say almost any application because some experts say a traditional green formula coolant still provides the best corrosion protection for older vehicles with copper/brass radiators."

(Image courtesy of Tracer Products) Dye has long been used to find small A/C leaks. Today, it can be effectively used to locate any fluid leak. Just follow best practices for best results.

Others I've talked to say universal coolants can be used but strongly encourage that a thorough flush and cleaning of the cooling system be performed first. And there are those that insist that only the OEM-specified coolant will do. Personally, I'm a fan of the latter but I'll leave the choice up to you.

The important takeaway I want you to leave here with today is that regardless of the claim on the bottle that the coolant inside is a "lifetime" fill, understand that the longevity of the coolant is impacted by the conditions it lives in. Missed leaks (internal or external), bad radiator caps, weak electrical grounds and other factors can all speed up the depletion of the inhibitor package each coolant formulation uses. And once it's gone, the interior destruction can begin.

So test your customers' coolants, not just for the pre-winter prep, but every time they bring it to you for service. It will add revenue to your bottom line and while extending the life of your customers' second largest investment.

Article Details

Fri, 11/01/2019 (All day)

Pete Meier

<p>As the weather turns cold, our attention turns to the needs of the cooling system. Is it ready to weather winter?</p>

<p>coolant, cooling system, leaks, automotive,</p>

A nominal amount of battery drain is present on every vehicle in the road once the vehicle is switched off and had enough time for its various modules to complete their “go to sleep” processes. The KAM (Keep Alive Memory) current draw for individual ECUs is typically around 1-3 mA per device. KAM is necessary for keeping both long term and short-term memory alive for functions such as the vehicle’s clock, DTC storage, telematics and module adapts to name just a few. The number of ECUs has increased in recent decades making the overall vehicle normal parasitic drain tally up to as much as 30 mA to 50 mA – the numbers that seem to be the unofficial max specs.  For this reason, many OEMs have moved toward greater use of EEPROM to provide more permanent memory storage and improved power management to decrease battery drain. This has helped to lower the normal parasitic on many newer vehicles to as low as 5-10 mA in some cases. Factory battery saver devices at the battery or in the BCM along with automatic module power down algorithms during extended storage times have also contributed to aiding today’s mobile electronic monstrosities in keeping their 12-volt starting batteries alive for storage periods of months at a time.

Intermittent battery drain – the phantom!

Parasitic drains on newer vintage vehicles seem to be intermittent more times than not due to the complexities of data buses and modules staying awake when they should be asleep. The most complex modern vehicles, however, can still have old school drains that can run a battery down in a few hours or few days. Even a brand-new vehicle (non HEV/EV) has an alternator that can suffer from a battery draining diode leak. Faulty door latch/door lock switches can cause drains as can glove box and trunk light switches. The old trick of opening a trunk or glove box and grabbing the bulb to see if it’s “two hours hot” or “two seconds warm” still works today just as it did 40 years ago.  Ouch: this test still burns your fingers too . . . but at least you found the drain!

The following steps will help you unmask your next phantom battery drain.

Step 1. Make sure it’s not something else. Document all DTCs in all modules. DTCs stored in modules after a battery drain are often “effect” DTCs rather than “cause” DTCs. Regardless, retrieve and document prior to clearing. Some DTCs that return may be good clues especially if they are U-codes (communications related) as we’ll see later. ALWAYS test the battery and charging system prior to performing a parasitic battery drain test. Many times, the customer complains of a battery drain or “short” when the actual problem is a faulty battery or charging system problem. A battery with an intermittent shorted cell can sometimes mask itself as a phantom battery drain. If there are any doubts on the condition of the battery — replace it! An underperforming charging system (faulty or incorrect alternator, poor connections, an undersized alternator or slipping drive pulley) can lead to false battery drain assumptions as well. If the vehicle is a HEV, PHEV or EV keep in mind there is a DC-DC converter that functions as an alternator. The same charging system tests complete with fully loaded electrical system conditions should be performed just the same as with a conventional mechanical alternator.

Step 2. False Ohms test — Prequalifying excessive parasitic current draws. DMMs (Digital Multimeters) read false resistance when you use their ohmmeter function on a live circuit.  You can use this tidbit of knowledge to quickly judge whether an above normal amount of current is flowing out of the battery.

Try this test in your shop: 

1. On a vehicle that has been sitting for an hour or more (all modules presumably asleep) connect an ohmmeter between the battery negative post/cable and a known good ground such as one of those short ground wires to a fender or radiator support. You’ll probably see the predicted 0.2 to 0.5 ohms of resistance which is mostly the resistance of your leads and alligator clips. 
2. Open the door to allow the BCM to wake up/dome light to come on. You almost always see a “false resistance” of several ohms on your ohmmeter. Switch on the ignition and you’ll see even more of this false resistance.  
3.  Turn off ignition, close the door and lock the vehicle with the keyless entry fob to speed up the sleep process. It may take several minutes but you’ll see that false resistance on the known good ground go back to the original minimal resistance you had to begin with (Figure 1).

Figure 1 - False resistance on grounds – your clue that there IS an excessive battery drain present The photo on the left shows 0.5 ohms between the battery negative cable at battery post and ground wire to fender. Meter’s leads connected (together) measure 0.4 ohms, so we have a good ground. Parasitic current draw was normal. (18 mA). The photo on the right shows the same ground resistance measurement only with a moderate parasitic current draw of around 1.5 amps. 28 ohms of resistance?  False reading tells you there is a drain!  it’s time to do a detailed parasitic current draw test

Now that you’ve seen for yourself how this trick works, use it on your next vehicle with a phantom drain. Simply watch the ohmmeter. When extra ohms pop up, there is an above normal drain occurring at THAT moment. Catching the phantom drain in the act BEFORE running time consuming and intrusive parasitic drain quantification and offending circuit isolation is the best way to avoid the frustration associated with unmasking the phantom.

Figure 2 - A calibrated quality inductive amp clamp with jaws large enough to incircle the battery cable(s) coming off either battery post in the hands of an above average tech is great. That holds especially true when attempting to scope the drain over time. Many of us will get in a hurry, however, and make the common mistake of not correctly converting 1 mV / 100 mV measured at the scope or DMM into actual mA.  The same holds true for those who use a shunt resistor in series with the  battery cable to measure mV of voltage drop. An extra decimal point in either direction can make or break an accurate diagnostic decision!

Figure 3 - The Fluke 87 DMM ammeter wired in series across a battery disconnect switch (400 mA ammeter scale used) is displaying  08.66 mA. The most accurate inductive amp clamp / DMM I own with large enough jaws to accommodate multiple battery cables is showing 00.03 A. That’s 30 mA which is a huge difference from the actual 8.66 mA. My advice is to use a quality ammeter in series as pictured!

Step 3. Keep the battery connected to “sneak up” on the phantom! Use of an ammeter connected in the typical fashion results in the battery being disconnected. One way to avoid that is to use an inductive amp clamp that converts the current draw to mV for conversion on a voltmeter or an inductive amp clamp self-contained DMM. There are a lot of inductive amp clamps out there on the market. I’ve found very few that have large enough jaws to fit around several battery cables AND is accurate down to a few mA  (Figures 2, 3). So, if you really want to accurately know how many mA the vehicle is drawing, use an ammeter in series (Figure 3) with the battery cable on the lower amp scale (most are 400 mA). Powering down the 12-volt system to connect a meter or shunt resistor (for a voltage drop/amp draw conversion); however, is a Murphy’s Law guarantee to make an intermittent excessive battery drain go into remission. Remission can sometimes last as longer than yours or your customer’s patience. Why risk having the phantom drain go into remission? Avoid depowering the system by installing a 12-volt battery boost box powered memory saver at the DLC (Figure 4). This will keep the 12-volt system alive while you install a parasitic load test adapter (battery disconnect switch).

Figure 4 - Battery memory saver / DLC  adapter.  Connect to a 12-volt boost box to keep vehicle alive during ammeter connections. Old style 12-volt accessory plug style (cigar lighter) memory savers don’t work anymore as many are disconnected from B+ when the vehicle is off

Next, trip driver’s door latch switch into the door shut position and jumper around any hood or other switches that are associated with gaining access to the battery and fuse panel(s). You are going to want to cycle the ignition on and off or drive the vehicle to get the phantom to appear so make sure you remember to close the parasitic load test adapter whenever cycling the ignition. Failure to do so will blow the fuse in your ammeter.

Figure 5 - The Midtronics In-GEN IDR-10 battery drain data recorder graph displayed for this 2012 Chevy Malibu indicate each of these spikes is separated by a period of 28 minutes. This is normal - a result of the ECC pinging the IPC for data regarding outside air temperature.  The average magnitude of these spikes is – 2.03 A. After the 4th and final spike, the current draw should return to the normal 10 – 20 mA draw.

Step 4. Know what’s normal. What really happens with the vehicle’s battery drain over the course of several hours of key off time? Try this experiment. The next time you find yourself waiting in a vehicle for 30 minutes or more try turning off the key and sitting in silence. Listen to what goes on. You’ll likely hear some activity. The occasional relay click and buzzing sound of the vehicle’s final checks on air suspension trim height, an evap leak pump/vent solenoid, HVAC doors cycling or even a short series of HVAC after-blow blower runs to prevent evaporator odor. While you may not hear these actions during your normal workday in a noisy shop, those activities are going on behind the scenes. A little overall knowledge on what equipment the vehicle has is helpful when you’re trying to determine if a measured spike in current draw is a normal activity or the phantom battery drain you’ve been trying to catch. Unless you’re using a scope on a long time base or another piece of equipment such as a data recorder (Figure 5), always use your watch to check the time and jot down when a current spike occurs. If the same current spike occurs EXACTLY every 10 minutes, (Figure 6) is only an amp or so and lasts a second or two, you probably aren’t looking at the reason for the customer’s battery drain. In the 10-minute example, a likely normal occurrence would be a Telematics (OnStar, Lexus Link, etc.) module waking up temporarily to determine if any calls to the vehicle from a call center are coming in.  Other normal parasitic loads occur every few seconds such as a theft deterrent LED blinking (Figure 7).

Figure 6 - Measuring the current draw over time on a 2012 Cadillac Escalade. When the battery cable is initially connected through an ammeter the current draw is almost 5 amps as various modules that are active with the key off power up. Within 1 minute we see most modules have gone to sleep but the drain is still excessive. After 10.5 minutes the current draw falls to an acceptable -0.018 amps (18 mA).

Step 5. Isolate the sub circuit (without pulling fuses). OK – so you have caught phantom in the act. Let’s say you have 350 mA (0.350 amps) running the battery down.  Time to determine out what circuit that drain is on and then identify what sub circuit/component is the root cause. Do you pull fuses? NO! That’s old school. Pulling fuses only works if you pull the guilty fuse FIRST! Remember Murphy’s Law of battling the Phantom drain? Don’t waste time battling module power down/power up/entering sleep mode over and over.

Figure 7 - This vehicle’s battery drain (after 10 minutes) went down to just over 7 mA but popped up to 9.5 mA periodically. Every 2 seconds this vehicle security light blinks. Placing the meter next to the blinking LED showed the increased current draw occurs just slightly after the light blinked (meter update delay) allowing us to correlate a normal event via meter observation.

Step 5a. Voltage drop test each fuse. If the fuse’s metal contacts are not accessible (plastic covers) you’ll have to pull each fuse individually. If the drain doesn’t go away, you’ll then need to reinstall that fuse and wait several minutes if the battery drain shoots back up even higher while any modules on that fuse power back up and then gradually go back to sleep. On fuses which you can access their probe test points (as you do when checking them for being blown) you are not looking for excessive voltage drop.  You are looking for ANY voltage drop. Any circuit with current flowing (even a tiny bit) will have “some” voltage drop. Take care to get a VERY good bite with your meter tips on each fuse’s set of metal probe points. Use your meter’s mV (millivolts) setting. When you’ve got a good contact on BOTH probes with the fuse the meter will settle completely on a number.  That number will either be 0.00 mV (no current flowing – Figure 8) or some very small mV reading that is rock solid and not changing.  A constantly changing mV reading is not an accurate reading of anything – it’s simply “digit rattle” which is the meter and leads catching stray EMI through the air. Take any mV readings you measure and refer to a mV to mA conversion chart. Power Probe has one of these charts on their website www.powerprobe.com/fuse-voltage-drop-charts. The chart allows you to factor the fuse’s type and amp rating along with your measured mV voltage drop reading and determine exactly how much current that sub circuit is drawing (Figure 8).

Figure 8 - Power Probe’s easy-to-use chart. 0.00 mV means zero current draw. On a 10-amp mini fuse, 2 mV of voltage drop on a fuse equals 270 mA of battery drain. More than enough to kill the battery in a few days! 0.2 mV would be fine though.

5b. Use advanced tools. A DSO (Digital Storage Oscilloscope) can not only be used to measure current draw over time (with an accurate enough low amp inductive amp clamp) it can also be employed to observe data bus activity. ANY activity on ANY data bus after 20-30 minute of ignition off (with any smart fobs OUTSIDE the vehicle) should be investigated. Going back to Step 5 (knowing what’s normal) is a big help here. Did the HS CAN bus become active for a few minutes in order to perform an EVAP test? In that case the PCM will temporarily be awake but shouldn’t run the battery down. Is there an intermittent faulty door jam switch waking up the BCM over and over making the LS CAN bus intermittently active? That will drain a battery. While the BCM is awake, plug in a scan tool and look for signs of improper door latch status if the OEM puts such a PID on the bus.  Another advanced tool to employ in your hunt for the phantom drain is a thermal imager (Figure 9). It will show relays stuck on (big battery drains) and even a power feed circuit with insulation chaffed creating a high resistance short to ground.

Figure 9 - Photo on far left and center shows a Snap-On thermal Imager’s built in library example of a known good image of a relay that has properly shut off compared to one that has stuck on. Photo at far right is a fuse panel after the vehicle has been shut off with no excessive parasitic current drain. Residual heat is shown across the entire fuse panel with the key off.  There was no difference however, in temp images of the dome light fuse – lights on or off.

Words of wisdom

My personal mentor in phantom hunting (my dad Ray Hobbs) always said the most advanced tool you can employ to unmask the phantom drain is your experience and ability to reason. Remember pulling all DTCs in all modules back in Step 1? Any module that continues to be involved in the setting U-codes even after the battery has been recharged/replaced is worthy of your scrutiny. A module what should normally be asleep with the ignition off (i.e. ABS) and continues to be implicated with U-codes may indeed be the phantom itself. Happy phantom hunting!

Article Details

Fri, 11/01/2019 (All day)

Dave Hobbs

<p>Let&rsquo;s review some time-honored methods as well as explore new methods for unmasking phantom battery drains.</p>

<p>battery drains, automotive, diagnostics, Dave Hobbs,</p>

Are you superstitious? I must admit that I am, just a little bit. What harm does it do to toss a pinch of salt over your shoulder after you knock the salt shaker over on the table? However, if you “knock on wood” to ward off evil spirits and something never happens, does superstition have anything to do with it? Some folks call that good luck and therefore, it has nothing to do with superstition.

The days of the Chevy Vega

When I was very young and impetuous, I successfully drove across the country. Some of you may have also done so when you were 21 as well, and most of you will think, so what? Well, I did it in a 1972 Chevy Vega. Do any of you older folks now affirm that it was indeed, quite a feat? Those younger might not know how problem-prone those cars were, but I can assure you they most certainly were.

It was on the second day of our trip when the car started to surge at a steady throttle. Having not even made it halfway across country (West Texas, to be precise) before trouble occurred, was not a good sign of how the rest of the trip might end up! The surge went away if I accelerated or decelerated. As it got later into the day, the surge continued to get worse. My wife and I were getting worried, so I pulled off to the side of the road to see if I could determine what was causing the problem.

Knowing if you’re working with a current DTC is important when making an accurate and efficient diagnosis.

A visual inspection revealed nothing was obviously wrong. The surge was dramatic at idle, causing the RPMs to raise and lower but not rhythmically and the engine was running very rough.

Tired, hot and exasperated, this inexperienced mechanic leaned against the air filter housing — and to my surprise the engine smoothed out. Completely surprised by what had happened, I lifted my hand off of the air filter and the engine started stumbling again! I repeated my actions several times to make sure it was not just coincidental.

I shut off the engine and took the air cleaner assembly off of the carburetor. I noticed the top two-thirds of the carburetor was loose because screws that passed through the throttle body into the underside of the carburetor bowl had vibrated loose and backed out. Air was bypassing the carburetor’s venturi between the two loose parts causing the engine to surge. On acceleration, the carburetor was enriching the mixture enough to prevent a surge. On deceleration, a high-intake vacuum pulled the loose parts together. While cruising, there was too much air entering the intake for the amount of fuel delivered. After performing an emergency repair, I felt fortunate and continued on my way. 

Found by accident?

Have you ever accidentally found the solution to a diagnostic problem? Have you ever gotten that lucky? I think all of us experience that every now and then. As a matter of fact, very recently it happened to me again. In my defense, I tried to fix this 2011 Chevrolet Malibu LT with a 2.4L, DOHC, 16v engine and 4-speed automatic transmission the right way, based on the information the vehicle provided, but that information led me nowhere near what was causing the problem.

2011 Chevy Malibu

The customer complaint was “check engine light on” without experiencing any problems driving it. The vehicle arrived in the shop with five ECM codes, three in the Power Steering Control Module, one in the Vehicle Theft Deterrent Module and two in the Generic OBDII side. It was quite obvious that some electrical faults were present recently. The technician cleared all codes out of all modules and found the ECM would immediately set two diagnostic trouble codes (DTCs) as soon as it was started.

Naturally, the shop eliminated all of the basic causes for so many problems such as a bad battery or faulty alternator before calling me. I did some research for them and found a technical service bulletin TSB referencing chafed wires underneath the rear seat, which may cause multiple faults, DTCs and/or customer complaints. The shop technician checked the harness in question and found absolutely nothing wrong with it. 

The two Engine Control Module (ECM) DTCs, P0615 Starter Relay Control Circuit and a P0230 Fuel Pump Relay Control Circuit, were shown on the scanner as stored in history and are current codes. After the technician spent several hours attempting to find a cause for the two codes (that would not clear), he then requested a time for me to visit so that I could program a replacement ECM.

Fuses and relays aren't always positioned so that their labels all face in the same direction. The Starter Relay is attached to this Fuse/Relay center.

There were several attempts I made and each time I was shown a different error message while attempting to program that module. I reinstalled the original ECM but experienced several more errors while attempting to program it. It was time for me to perform some diagnostics.

Getting a hand on the problem

It seemed very odd to me that the car cranked and started up as if there were no problems, yet we had hard codes for the starter circuit and fuel pump circuit. I began with a visual inspection. I noticed some of the relays with their writing in the opposite direction of all others. That immediately raised a suspicion that somebody else had been here before me. I looked at the service information wiring diagram — and the diagram printed on the relay — and determined both relays were installed incorrectly. I thought to myself how lucky is that! I cleared codes with a smile from ear to ear.

My elation quickly changed when I still had the same codes setting again after I started the car. The shop owner asked if I had any luck. I answered, “Yes, all bad.” After all, being unlucky is one form of luck isn't it?

The Fuel Pump Relay is attached to this Fuse/Relay center.

As a side note, those relays made no difference in the way the car started and ran. Don't ask me why reversing the direction of the relay makes no difference.

I began following the troubleshooting charts for both DTCs, which led to "Replace and program ECM," the same as the shop's technician determined. I didn’t believe that conclusion after what I’d tested already. The technician and I spent a few moments going over each of the steps that we both had performed and having obtained the same results, we were perplexed.

Tired, hot and exasperated (and like before, with no direction to go) I leaned on the core support — and immediately pulled my hand back off. It was hot enough to burn my thumb, which was unusual, because the engine had not been run for several hours. I was doing testing with the key on, engine off!

Melted insulation near the wire terminal is proof of the extreme heat it suffered.

Although when I initially saw it, I paid very little attention to the fact that the negative battery cable had been replaced. It was obvious because of the aftermarket battery terminal connection. Now, however, I focused on that previous repair! A closer inspection of the ground terminal on the radiator core support revealed it had suffered heat damage from a loose installation. No further testing needed to be done. I replaced the wire terminal and relocated it to the stud next to it. I then cleared codes and started the engine.  Rechecking for any DTCs proved none were present.

Clearly obvious is the misaligned factory marking the outboard (left) ground to the core support, indicating it had been tampered with. A clearly overheated terminal is attached to the inboard ground lug.

The clues I had earlier — the DTCs the shop recorded when the car arrived (then cleared) — could have led me to this sooner if I would have prioritized one of them (a P0315 “Crankshaft Position (CKP) System Variation Not Learned”). It has been my experience that when a computer claims that crankshaft variation has not been learned that there has been a cause for its amnesia. It was this problem that I could have attempted to address first. However, history codes are just that. They occurred sometime in the past; nobody knows when. I could have also wasted a lot of time with that testing, too.

Arcing is evident on the Ground Lug.

Once I repaired the radiator core support ground, I performed several different tests on the ECM power supplies battery, the ignition feeds and all of its grounds — which all passed. I called this job done!

Whether it’s called diagnostics or it is called sheer luck matters NOT when the ultimate result is - the car’s repaired.  There was absolutely no mention of it in the diagnostics — for either recurring DTC — instructing the technician to check the battery grounds. My finding a poor connection that once repaired solved the problem, was purely good luck. I’ll take luck over a non-billable diagnostic session any time! Oh, and my thumb healed quickly.

One of our diagnostic tools can be our sense of touch.

By the way, it was that trip I took in my younger years from California to Florida that got me my first mechanic job. The shop owner said if I knew enough to make a '72 Chevy Vega go across country in just five days that I "must know something"! He hired me on the spot!

Article Details

Fri, 11/01/2019 (All day)

Jaime Lazarus

<p>Despite our best efforts to follow published diagnostic routines, there are times we can&rsquo;t determine the root cause of a problem &mdash; and then we get lucky!</p>

<p>automotive, diagnostics, luck, Jaime Lazarus,</p>

Technicians never can have enough support. 

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Motorcar Parts of America has launched cutting-edge technical support to help today’s techs nationwide repair vehicles faster and more accurately. 

Get a quick look at the new technical offerings from MPA in a short video highlighting technical how-to sheets, general installation best practices and much more. Vehicle-specific issues are covered as well. 

In addition to the latest video highlighting the technical support, techs now can see overviews of product features from brake calipers to turbochargers and more. Two new videos highlight brake calipers and turbos, with more coming soon exclusively through Motor Age. 

Check out the videos and see the new technical support you can take advantage of. More videos are being added, and the overall technical support is growing. 

Need more? There are additional technical bulletins and tips available on the video page, including electrical systems and more. 

All of those topics cover many technical aspects MPA offers increased, cutting-edge support on. Watch, read and get the support you need now. 

Article Details

Tue, 11/19/2019 (All day)

Tschanen Brandyberry

Motorcar Parts of America has launched cutting-edge technical support to help today’s techs nationwide repair vehicles faster and more accurately.

MPA, Motorcar Parts of America, technician training, training, training videos

What We Have Established So Far
We have discussed how electron current flows through the ground circuit and how to measure ground electron current. We discussed a few points about the DMM and the importance of grounding the DMM at 0.00 V when measuring ground side voltages. The two locations on a vehicle where this ideal ground voltage is available are -GEN or -BATT. If there is no Vd (voltage drop) between these two electrical points use the easiest one to access for the DMM ground.

On a new vehicle, it is reasonable to expect the voltage drop between -GEN and -BATT to be a true 0.00 V reading and we could use either point for our DMM ground. This can be confirmed by a simple voltage drop test with the engine running as previously illustrated in Part 10, Figure G05V.

As a vehicle develops some mileage, connections and cables begin to develop corrosion that impairs the flow of electrons passing through them. This causes Vd readings to begin to rise and we discussed the increase in Vds in the last segment. The higher the level of corrosion the higher the Vd. We established the fact that a good electrical ground should not be higher than 0.10 V although a number of electrical circuits can operate properly with the ground voltage above 0.10 V. A good computer ground should not be higher than 0.05 V although some computers can continue to operate if the ground voltage exceeds 0.05 V. A small Vd allows for a slight amount of corrosion in the ground cable and connections as a vehicle ages.

Only by experience can it be determined which electrical circuit ground or which computer ground circuit would be adversely affected should the voltage drop exceed these limits. The important point to consider is what the ground side voltage drop should be and ensure that the ground side voltage is as low as possible.

Corrosion is inevitable resulting in higher voltage drops as electron current flows through increasing corrosion. Forget about measuring the resistance of the corrosion in a wire or connector with an ohmmeter. The ohmmeter method is too unreliable. An ohmmeter could indicate very low resistance ground connection when it is bad but the voltmeter would indicate an excessive Vd. The opposite is also true. The ohmmeter could indicate some resistance indicating a corrosive connection yet the Vd would be acceptable. Believe the Vd reading of the DMM to confirm a good cable or connection. Do not rely on an ohmmeter test.

Remember corrosion produces resistance in a circuit. Corrosion begins to reduce the electron current that can flow through the circuit so circuits begin to become less efficient. Measuring electron current only tells you if the electron current is normal or if it’s too high due to component failure or too low due to corrosion developing in the circuit. It doesn’t tell you where a problem is in the circuit. That is why we use voltage measurement to find circuit problems.

How Much Vd between -GEN and -BATT?
For purposes of discussion let’s say we find a Vd of 0.10 V between -GEN and -BATT. This would indicate some corrosion has begun. There are two circuits to check. 

1. Generator Ground: With the engine running, measure the Vd between the generator housing and the engine block. I would like to see 0.05 V or less. If the Vd is higher it could indicate corrosion where the generator housing connects to the generator support bracket or where the support bracket bolts to the engine block. Check bolts for tightness. If necessary, add star washers to the bolts to improve electrical connection as the bolts are tightened. Verify Vd of 0.05 V or less.

2. Battery Ground: Measure the voltage drop between -BATT and the engine block. I would like to see 0.05 V or less. If the Vd is higher it could indicate corrosion at several possibilities. There could be corrosion on the surface of the battery negative post; corrosion on the inside surface of the negative terminal clamp; corrosion where the cable enters the back of the negative terminal clamp; corroded negative cable; corrosion where the negative cable enters the ground terminal on the engine block; or corrosion between the ground lug and the surface of the engine block. Clean connections and verify Vd of 0.05 V or less.

If the Vd between -GEN and -BATT is greater than 0.10 V and has been reduced to less than 0.05 V after cleaning connections, check to see if the electrical problem in the vehicle has been corrected. If the electrical problem remains, at least you have established the main grounds in the electrical system are in good condition and you can safely ground at -GEN or -BATT and rest assured all voltage measurements you take will be a true reflection of the circuit condition where you are testing the circuit with your V/Ω (red) test lead. Do not think this is just a lot of unnecessary extra work. I have seen this attention to detail in the ground circuit repair numerous electrical problems over the years. This is especially true in older vehicles and vehicles subjected to extreme road conditions.

Pay Close Attention To Ground Voltage Readings
A lot can be learned as ground voltage is tested correctly. In Figure G10V below, the ground voltage is measured on the ground side of the load in Circuit #1 and Circuit #2. The DMM is grounded at -BATT. The ground side could be a logical place to start troubleshooting a circuit that appears to be not operating at all (Lamp is OUT) or not working properly (Lamp is DIM). But it’s always a good idea to always check known good circuits to learn what voltages you can expect in a good circuit. This makes it much more effective recognizing when a Vd is too high.

Figure G10V

Notice the two ground side voltage readings above. These two readings tell us the ground circuit is good while electron current is flowing. The reason the voltage on the ground side is very small is due to the fact the ground circuit has very little resistance provided all ground connections are clean and tight and the wiring on the ground side is not damaged. These two readings confirm the ground side of the circuit for each circuit load is good.

By paying close attention to the ground side voltage readings we can reach some conclusions. DMM #1 indicates 0.04 V. From this we know the -BATT terminal is making good contact with the -BATT post. We know the accessory ground cable from -BATT terminal to G101 (sheet metal (1)) is good and ground connection G200 to sheet metal (1) is also good. We know switch, S2, is a good switch and the wire between G 200 and Pin 2 of Lamp Circuit #1 is a good ground wire.

DMM #2 indicates 0.05 V. The increase of 0.01 V from DMM #1 reading confirms the ground strap between Sheet Metal (1) and Sheet Metal (2) and ground connection G300 are both good and the ground strap adds 0.01 V to the ground circuit reading at Lamp Circuit #2, Pin 2. There is no need to do a voltage drop test between Sheet Metal (1) and Sheet Metal (2) to confirm the condition of the ground strap. The good reading at Lamp Circuit #2 confirms the ground strap is performing properly. 

With this one circuit voltage measurement at the ground Pin 2 of the load for Circuit #1 or Circuit #2 while the DMM is grounded to -BATT confirms the ground circuit is in good condition for each circuit tested and saves time with other tests to confirm various portions of the ground circuit are good.

Detecting A Ground Side Problem
In Figure G11V below, we have a problem with Lamp Circuit #2. Lamp #2 is dim. The circuit voltage on the ground side of the lamp, Pin 2, is greater than 0.10 V indicating a ground side problem. Keep in mind what we said about the lamp circuit in the beginning of this series. We are using lamps to illustrate how circuit problems affect the lamp (load) because it is easy to visualize the lamp is working dim.

Figure G11V

DMM #1 tells us what is good on the ground circuit. We can conclude the accessory ground cable, G101, G200 and Switch S2 are good based on the Vd at Pin 2 of Lamp Circuit #1.

DMM #2 tells us the ground circuit for Lamp Circuit #2 has a problem. The reading of 3.82 V clearly shows that Lamp Circuit #2 has a ground side problem. Possibilities to investigate would be the ground strap connections at either end, the condition of G300 and the wire between G300 and Pin 2 of the Lamp. Somewhere in the ground side of Lamp Circuit #2 expect to find a corroded connection or a damaged ground wire. From experience, I would expect to find a corroded connection on the ground side of the circuit.

The voltage of 0.04 V at Lamp Circuit #1, Pin 2, tells us a portion of the ground circuit is good at Sheet Metal (1). The bad ground reading at Lamp Circuit #2, Pin 2, narrows down the possibilities of what portions of the ground circuit are left to test. Further troubleshooting steps are required.

At no time did we need to measure the electron current in any part of the circuit to identify the circuit with a problem. If the electron current was measured, we would get a lower than normal current reading in Circuit #2 but that doesn’t tell us why the electron current is low or why the lamp is dim. That’s where voltage measurements must be done. Voltage measurement identifies the circuit fault as a ground side problem causing the dim lamp. The dim lamp is used to simulate how other circuit loads would be affected as we discussed earlier.

Suppose Lamp #2 was a DC motor instead of a lamp and placed in this circuit as the lamp is. How would the DC motor perform? Obviously, the DC motor would run slow (low rpm).

Suppose Lamp #2 was a solenoid. How would the solenoid perform? Obviously, the solenoid would be very sluggish and may or may not be able to perform its desired function.

FIgure G12V

Suppose Lamp #2 was a relay circuit which has two individual circuits; the relay coil circuit and the secondary circuit connected to the relay contacts. If the bad ground was on the relay coil circuit it may or may not prevent the relay from energizing. If the bad ground was on the relay contacts side of the relay circuit it would induce poor electrical performance in whatever circuit the relay is controlling.

Suppose Lamp #2 was an onboard control unit. How well would it perform if the main ground circuit was experiencing a significant voltage drop? It would be impossible to re-flash this control unit. Circuits that the control unit is supposed to turn ON or turn OFF may or may not happen.

You see the point? The lamp is used to simplify the teaching of circuit concepts. In future segments of this training program we will change the lamp into various electrical components and discuss some advanced principles of vehicle circuit troubleshooting.

In the next installment of this series we begin studying the circuit below. Look it over. We will focus on how circuits interact with each other in Figure G12V.

Article Details

Mon, 11/25/2019 (All day)

Vince Fischelli

<p>In Part 12 of this series on ground circuits, we look at measuring ground circuit voltage.</p>

<p>ground circuits, Vince Fischelli</p>

Growing up as a teenager in the ’70s, I learned that my parents were not in a position to buy me a new car and I quickly conditioned myself to work hard for something I wanted and went on a mission to cut many lawns, deliver newspapers, provide grocery valet service in the ShopRite parking lot and even selling seeds door to door. This is what we did as teenagers to have the revenue to purchase what we wanted. I saved up enough money to buy myself an old 1953 Dodge pickup with a straight L-6 engine and a 3-speed manual transmission. This truck was fully serviceable and just about anything on that truck was rebuildable. I soon learned that a nearby antique “junkyard” was my best friend to keep operating costs low to perform any repairs I needed. It was the way of life growing up to earn, save and spend wisely.

Many things have changed over the years and now these “junkyards” are considered a gold mine for parts that are needed. These yards are now labeled as “salvage yard” or “recycled parts” and we dare not use the word “junk” anymore. Many collision shops are now being given the option to purchase used parts to keep operating costs low on insurance claims after an accident. There are also customers at repair shops that ask for an option to put used parts in the vehicle and it all boils down to the costs of repairs. There is nothing wrong about this operation because you're putting in the same manufacturer parts that still meet the quality of the vehicle but the buyer must be aware that the parts they buy may not be the correct ones at times and that they may be compromised by a prior accident or ruined by weather conditions.

Figure 1

Saving money or asking for trouble?

A homeowner was looking to save some money on purchasing a newer vehicle so he decided to buy a 2016 Audi S7 “Salvage Vehicle” for a very good price but it had a few underlying issues that he was aware of when he agreed to the price of the vehicle (Figure 1). These salvage cars can sometimes be a train wreck in itself or you can get lucky. It’s a buyer beware deal and you need to know what your purchasing and what issues the car has that might create deep pockets on your behalf. The one issue that was known with this Audi was the transmission case was cracked and leaking fluid from a prior accident and it was never addressed. The only fix was to replace the entire transmission assembly. If purchased new or rebuilt this might have been a very expensive venture so the owner of the vehicle opted to find a salvage transmission and hire out a transmission shop to install it for him.

Figure 2

The transmission shop was not obligated to give him ANY guarantees with the job because it was a salvage transmission and they were not taking any responsibilities and the only guarantee was the installation of the unit. The owner agreed and he dropped off the vehicle on a flatbed and it drove off the flatbed without ant issues and parked in the parking lot of the transmission shop. The salvage transmission was also dropped off for the shop to install (Figure 2). All things were now put into play and the customer was excited to get his investment of a low-cost vehicle on the road just in time for the summer. During the week the transmission was installed by the shop and the installation went smoothly but once the job was completed and the fluids were topped off, the vehicle would not go into "Drive" or "Reverse.” The owner of the vehicle was soon notified and then it became a blame game. The owner stressed that the vehicle did have "Drive" and "Reverse" gear issues before the installation and the transmission came out of a good running car. It was that “drive them in/push them out” syndrome but the transmission shop had already explained that there were no guarantees with a used unit.

Is it the tranny?

It was at this point that the owner of the vehicle Googled my service on the Internet for technical assistance. I interrogated the owner as much as I could to get all the information I needed to start building my Diagnostic Game Plan. Then I told him that I strictly work with shops but I would be willing to help him to get his problem resolved but explained to him that I needed to get the shops’ authorization to work on the car there. I called the shop and explained about my services and I had to do a second interrogation process to kind of dot the “i’s” and cross the “t’s”. The shop was willing to allow me to work with them but it was up to the owner of the vehicle to pay for my services. The shop was looking forward to meeting me for future support on their shop vehicles so it was a win-win situation for me but I needed to tackle this job first because I was now on proving grounds for two new parties involved with this “Salvage Audi.”

I had the Audi/VW factory ODIS tool so I was in good hands if I needed guided functionality. This was not just a basic scan tool but a tool that was PC-based, online and reprogramming capable. It also had a feature where you can click on a Trouble Code and it would guide you to resolve issues in a step-by-step procedure. The transmission shop was very knowledgeable and they believed that the transmission had to be programmed to function but this is a myth for most manufacturers because usually I encounter a mechanical or electrical issue for an inoperative transmission. But I was willing to give him the benefit of the doubt. Many transmissions have control modules within them that if not flashed with software may not function properly and then others have external transmission control modules but need the valve body I.D.’s configured to the transmission module or premature failure of the transmission may be inevitable.

Figure 3

Figure 4

I placed my scan tool on the Audi and retrieved a Code P170100 for “Transmission Control Unit Locked” (Figure 3) in the Transmission Control Module and also a Code 2229 Transmission Control Module Immobilizer Data Not Adapted (Figure 4) in the Immobilizer Control Module. I did not expect these codes on this vehicle at all and this was not about reprogramming but rather configuring the transmission control module to match the vehicle.  It was the manufacturer’s way of protecting parts from another vehicle to be sold on the open market just in case they were stolen. This transmission was locked into “Neutral Mode” and had to be unlocked by the Audi server. This would now explain the “Safe Mode” indicator above the mileage on the dash that I was unfamiliar with (Figure 5). Lucky for me I had the factory tool along with a Security Professional License through VW’s Gecko Security system that would allow me to perform the functions needed to get this transmission to work.

Figure 5

Figure 6

Let's fix it!

I navigated to the Immobilizer Functional Procedures menu and selected the Transmission (Figure 6). There were many other control modules protected on this hit list so it just wasn’t about protecting used transmission modules but many others on the vehicle that were on the proprietary list. One of the prerequisites to allow the procedure to start was the possession of the car’s registered key that had to be held by the key antenna insignia at the center dash panel (Figure 7). The key would have to be placed here until the scan tool told you it was done recognizing it. Usually, the placement of the key is with the Audi insignia facing out and in the upright position so that the key antenna can pick up the strongest reception of the key fob (Figure 8). Many manufacturers use this method to program new key fobs but sometimes these antennas can be tucked away in a glove box out of view or by the cup holder so you must know exactly where to place the key fob during the learning process.

Figure 7	Figure 8

Once the procedure was performed and I cycled the key, the “Safe” indicator on the dash was no longer visible and the transmission now shifted into Reverse and Drive. I next proceeded to clear the entire vehicle and perform some parking lot maneuvers. This vehicle had no temporary plates and was not registered yet so I was limited to fully testing the transmission so I left it up to the shop to find a way to make sure the vehicle had no shifting issues on the road. I did, however, perform a last full vehicle scan to make sure there weren’t any other underlying issues that the owner of the vehicle should be aware of. The only issue I did come across was a Code U023500 Font Distance Sensor (Figure 9). This would answer the question of why there was an Adaptive Cruise Control red icon on the dash in the speedometer area (Figure 10). I’m guessing whoever repaired the vehicle might have left the Cruise Control distance sensor out of the repair process to keep their operating cost low for the salvage vehicle sale because it was not communicating with my scan tool when I tested it.

Figure 9

Figure 10

My job was done and I had a happy owner of the vehicle and I forged a new relationship with another repair shop in the process. I can only tell you that technology is getting really out of hand now. A simple R&R is not as simple as it was back in the day. You now have to make sure that any electrical part you buy used is correct for the vehicle you are using it on and you need to make sure it is not one-time use. Many manufacturers will not allow an embedded VIN on a used component to be overwritten such as BMW, Mercedes, Land Rover, Jaguar, and a few others but many salvage yards may be unaware of this and sell you the part anyway. Then other manufacturers such as Audi will lock down a part and render it inoperable until their server brings it back to life with an Audi user having proper credentials to do so. My only hope is that this story has enhanced what you know or don’t know. Buyer beware!!!

Article Details

Sun, 12/01/2019 (All day)

John Anello

<p>A homeowner was looking to save some money on purchasing a newer vehicle so he decided to buy a 2016 Audi S7 &ldquo;Salvage Vehicle&rdquo; for a very good price but it had a few underlying issues that he was aware of when he agreed to the price of the vehicle.</p>

<p>salvage parts, auto repair, Audi S7, diagnostics,</p>

We are pleased to announce that on Nov. 18, 2019, we launched our newly redesigned van lockers and workbenches. These products are great for storage and organization within the mobile technician’s work vehicle.

Our lockers have been updated with our new black end panels, in keeping with our product line consistency. We have also increased the width by 2 inches to add a little extra storage space, and have upgraded the install brackets to newer and tougher versions.

For both the new lockers and workbenches, we have standardized the doors to match our shelving doors. This helps reduce inventory and makes install simpler for both our customers and distributors.

Our new workbenches have not changed drastically, as the smooth, wood top design is timeless. The end panels have altered slightly to accommodate our new brackets; however, they will still remain aluminum for increased payload and overall durability.

Whether you need a stand-alone storage compartment to hang your work gear, or a customized bench in your van, Ranger Design has got you covered!

Learn more:https://rangerdesign.com/van-storage-bins/

About Ranger Design
Ranger Design is known as an innovative designer and manufacturer of specialized van shelving, van racking, ladder racks, partitions and storage systems for commercial vehicles. With a network of over 300 distributors across North America, Ranger Design provides products that offer the highest degree of quality, an industry leading warranty, and world class customer service.

Article Details

Mon, 11/25/2019 (All day)

ABRN Wire Reports

<p>We are pleased to announce that on Nov. 18, 2019, we launched our newly redesigned van lockers and workbenches.</p>

<p>Ranger Design</p>

A 2010 Mercedes Benz E350 4matic with 64K on the clock came in with a complaint of the right front headlight and blinker not working. We informed the Benz owner that it can be as simple as replacing the light bulb or clearing codes and in some cases, a module that controls the lighting may have to be coded, programmed or replaced. Now that the vehicle owner had a better understanding of why there was a diagnostic fee, we were able to begin our diagnosis.

If you’re not familiar with dealing with Mercedes-Benz vehicles you need an understanding of what we had to diagnosis to get the lights working again. Let’s start with the SAM (Signal Acquisition Module), and what it does, so if an MB comes into your shop you know what you are dealing with. The SAM module receives data from sensors, switches, and controllers, then send a command to activate components such as a light bulb. On this Benz, there are three SAM modules, two in the front, left and right along with another in the rear that controls different components. On this E350 the one we were concerned with is located at the right front footwell area next to the fuse box. The SAM module operates on a CAN B slower speed (Controller Area Network) BUS that exchanges information from switches, relays, horns, lights, heated seats, cooling circulation pump and more. Just like any other network on today’s vehicles if you change a component you may have to either code or program it on the BUS if you want it to work. Remember it’s not a matter of just replacing light bulbs anymore more, in this case, the SAM module had codes in it that were preventing the new bulbs from illuminating and operating as designed. The procedure entailed connecting a suitable scan tool that has the capabilities to clear and reset the SAM module. We decided to connect our AutoLogic scan tool to diagnose the problem and clear the codes for the lights to operate. Once the procedure was completed the lights worked and the message on the central display module on the dash was cleared.

Another lighting issue

On other Benz’s we have come across, the brake lights stayed on or were inoperative due to a defective rear SAM module. The fix on most of those MBs was ordering a new SAM, replacing it, followed by carrying out the SCN coding (programming) procedure. So, remember that if you come across a headlight, taillight, directional light, mirror or other component that does not operate after you replaced it, you most likely have to connect your scan to and check for codes, along with checking if the module needs to be coded or programmed. I suggest consulting service information such as Identifix, ALLDATA, ProDemand or MotoLogic so you can check for the most common issues and read up on system description to prevent wasting time and replacing parts that are not defective. Another good tip that I would like to share is what I do on any component that does not operate.

First, I connect a Power Probe to the battery and confirm that I have a good connection by taking the ground wire clip that is connected to the probe’s body and connect it to the tip. With the wire connected to the tip, the green led should be illuminated confirming you have continuity, but wait you’re not done testing that connection. Next, depress the power button and see if the 8-amp breaker pops. If the breaker pops, you have confirmed that you have a good power and ground connection. Now you can proceed to the next step of making sure you have power and ground to the component. With the key or power button in the off position, disconnect the wire connector from the component you want to test, then turn the power back on, check what side of the connector has power. The reason for the previous step is to make sure you connect the Power Probe’s power and ground to the correct side of the component that you want to check. If you don’t perform this step you may just burn out the component due to a diode that is installed in the component. Now it’s time to replace the headlight making sure the correct wattage bulb is used for the replacement. Volts times amps equal watts, why is this important? If you install the wrong wattage bulb such as a headlight, you can melt or burn up the headlight socket, wiring or lens housing.

To get the light operating again on this Benz E350 it was not simply replacing light bulbs or checking voltage and components, but using information learned or looked up in service information along with using a capable scan tool that was able to read and clear codes in the SAM module.

A GMC that refuses to start

Our next tough one was a 2014 GMC Acadia 3.6L with 49K (Figure 1) that was towed in as a no-start, no-crank. After speaking and questioning the vehicle owner we found out that there was nothing recently done to the vehicle and the same gas was in the vehicle as when it started before the no-start condition. During our questioning, we asked her if the vehicle had any dash lights illuminated or messages displayed at any time before this no-start condition. She relayed that there was some message on her dash display. After a few minutes of thinking, she replied that the message displayed on her dash stated something like “Service Side Detection System” now and then but thought nothing of it.

Figure 1

Well, that information was a good key to unlocking the no-start condition on this vehicle. Now, I can tell you if you’re thinking the no-crank/start is due to a battery, starter, fuel, spark, air or mechanical condition, you're dead wrong. Newer vehicles that we work on are different than vehicles of yesteryear. This vehicle is not your father’s Oldsmobile, Pontiac, Plymouth, Saturn or any other vehicle that is out of business, you’ll be out of business if you use the same old diagnostic approach. So, as you can gather from the previous sentence, you know that the problem is not related to any of the old normal systems or components. This is where using your brain, eyes, and hands comes in to play by using a scan tool to check for DTCs followed by looking up information on Identifix, iATN or other information systems.

The next step before replacing any component is to read a system description to help you get a better understanding of the system. We uncovered additional information on Google that stated there were problems with the Object Detection Module on many GMCs that the owner complained about. After reading that on Google we went back into Identifix and found a no-start condition from the left side detection module listed. Even though it was not an exact match for our B094C Right Side Object Detection Module, it was close enough.

Our next step was to make sure that there was no mud, snow, ice or other obstructions preventing the system from operating as designed. Checking for debris on the unit is an important step since this system uses a radar signal that is sent out to check for any obstructions. With no obstructions found we followed what Identifix had in their information about the system.

The system operates on the GM LAN low speed CAN system that communicates on the BUS. After checking for communication on the BUS we found that there was no signal and had to continue checking the system. The next step entailed locating the splice pack for the system which allows for module removal via the splice pack comb. When the comb is removed the modules no longer communicate on the BUS since they are disconnected. With the comb removed the vehicle communication returned, so we knew something was taking the BUS down.

When communication returned, it confirmed that the other modules that we disconnected one at a time were good and that there were no shorted wires. The only module that failed was the Right Side Object Detection Module, so we called the dealer and ordered a new one. After installing the new module, we programmed it so the BUS could be functional again. We followed all the regular procedures for programming that we have used many times before, such as using a battery maintainer and making sure that all the accessories were turned off along with doors, hood, and rear deck closed.

Figure 2

Once the module was programmed the vehicle started up, but the radio would not work. This was something that we don’t normally encounter as a problem. After we entered the radio data via the scan tool, we found that the VIN was not present and that the radio power mode was not switched to normal in the configuration information. We typed in the VIN and changed the configuration to normal and the radio came back to life. The customer asked us to program in all her AM, FM and Sirius channels (Figure 2) which we did and then returned a running GMC to her.

A misplaced shift?

A 2005 Chrysler Town and Country 3.3L with 90K came in with a P0305 Cylinder Misfire, P0700 Transmission Fault and P1776 Solenoid Switch Valve Latched in LR Position. We did our due diligence and found a TSB 21-001-13 that deals with a solenoid that is located in the valve body and not in the solenoid pack where all the others are located. The issue deals with the manual valve in the transmission not in the OD position that sets the DTC. The TSB suggests that the shifter adjustment be checked and adjusted if needed. We also checked to make sure that there was no debris in the transmission fluid. Our next step was to follow the TSB and recommend that the transmission controller be reprogrammed with the updated file that Chrysler suggested for this DTC. Since this vehicle owner was on the fence about keeping this vehicle, he decided not to perform any repairs and traded the vehicle in. The takeaway from this vehicle is if we did not check TSB’s we would have not known there was an update and possible suggested a different path of repair.

Does it need a "flash?"

A 2007 Toyota Tundra 5.7L with 159K (Figure 3) was towed in from a used car dealer with a no-start complaint. Anytime we get a vehicle from this particular used car dealer they always think that reprogramming is the issue that is going to fix the problem. As we proceeded to check the vehicle out, we noticed that the VSV and Traction Control lights on the dash were illuminated. We had seen this before on another Tundra that was running that had the same dash lights illuminated and was stuck in low gear. This Toyota was a no-start, but the two Tundras may have something in common. We called the used car dealer and told them that reprogramming was not going to solve the no-start condition on the Tundra. We requested two hours of diagnostic time to locate the no-start issue on this vehicle.

Figure 3

Figure 4

One they approved the two hours we connected the Toyota Techstream scan tool and received a message that stated "waiting for an acknowledgment." As we started to check the vehicle out, we found a communication issue, so we performed a CAN ohm meter test that provides a 63 Ohm reading (Figure 4) that indicated no problem.

Figure 5

Figure 6

The next step was connecting a labscope to diagnosis and check for communication packets on the BUS. We made sure power and ground were good then moved on checking the 5-volt reference signal. The results of that test displayed no 5-volt reference, so we started unplugging all 5-volt reference signals to see if the communication (Figure 5, 6, and 7) would restart, but no luck. This meant that something else was pulling down the 5-volt reference, which indicated something had to be shorted.

Figure 7

We located a comb for the BUS that was located under the glove box that allowed us to disconnect modules. Bill decided to unplug each connection one by one to see if there was any change, unfortunately, nothing did. Bill called me out to the parking lot where the truck was parked and asked me to check the vehicle with him. As Bill proceeded to show me all the tests he performed, I remembered that I had encountered another Toyota that had a similar problem. I made mention at the beginning of this case study that the other Toyota also had the same lights illuminated on the dash, but that truck started. I recalled what the issues were on that truck which led me to go out under the hood and locating the AIR system.

Figure 8

My next step was to disconnect the 12-volt wire (Figure 8) that goes to the solenoid, then have Bill crank it over. Bingo, the engine started right up, and the 5-volt signal returned along with all the other systems up and running. But what caused the solenoid to short out?

Well, this is nothing new to me or anyone who worked on AIR emission systems. Usually, the problem is that the check valve diaphragm is burnt out, causing hot exhaust gases to get through to the solenoid, melting it and causing it to short out. This was indeed the cause of the no-start and the 5-volt being pulled to ground. We suggested that both check valves on the system be replaced along with the Bank 2 shorted solenoid. The used car guy decided just to leave it unplugged and sell the vehicle as-is. You can’t fix stupid!

Finishing up with a Porsche

Our last problem vehicle is a 2004 Porsche Cayenne with a 4.5L V8 with 145K on the clock that was towed in as a no-start. Our starting line on this vehicle was speaking to the vehicle owner who was not forthcoming with any helpful information.

We started with the heart of the electrical system and found that the battery only had 4 volts present. My tech Bill proceeded to charge the battery up then checked for voltage at the battery jump start post only to find a reading of 0 volts. Bill then moved on to check if there was any voltage at the fuses under the hood, once again only to find the same results of no voltage.

Figure 9

Researching in Identifix and iATN came up empty so we had to follow the electrical trail that leads to the battery and a reset circuit breaker. Bill continued to check the vehicle out and found that the left front height sensor that is located on the control arm (Figure 9), had a broken connector and corroded connecting pins. The owner refused to repair this issue and just wanted the vehicle to start. We installed a new battery and reset the circuit breaker (Figure 10), checked the charging system and invoiced the customer.

Figure 10

I hope these case studies help you get a better understanding of some of the systems allowing you to check them and helps you diagnose and repair them faster.

Article Details

Mon, 12/02/2019 (All day)

G. Jerry Truglia

<p>Some scary diagnostic challenges often turn out to be easy to handle. And the &quot;easy&quot; ones often turn out to be the toughest!</p>

<p>auto repair, diagnostics, electrical, truglia,</p>

I have had many conversations with both technicians and trainers about the issue of misfires caused by intake tract deposits on Gasoline Direct Injected engines and what causes the misfire. There are several schools of thought, from compression loss across the intake valve seat from deposits, to intake valves sticking in their guides from carbon, to airflow disruption in the combustion chamber. Whatever is causing the misfire, many technicians have encountered this problem and corrected the misfires through intake tract and valve cleaning.

It is this problem that I was contemplating when a 2013 Chevrolet Captiva showed up at my shop. The customer was another shop that had worked on the vehicle and decided to get a second opinion concerning a misfire on cylinder #2. The shop stated the engine misfired during warm-up and had a noise from the engine. They replaced the ignition coil and spark plug with no improvement and were confused by the symptoms the engine exhibited. This compact SUV has a 2.4-liter GDI, naturally aspirated engine with only 45,000 miles. The most interesting symptom was a sharp popping noise that seemed to come from the intake system and could be clearly heard around the air intake throttle body. The noise accompanied the misfire and made me believe there was a mechanical problem with the engine such as a valve sticking due to intake deposits. I recorded the noise with my cell phone when the engine ran but cannot include it in the article, but trust me it was there and very apparent. The scan tool confirmed the problem and can be seen in Figure 1.

Figure 1 -  Scan tool capture showing greatest misfire counts on cylinder 2

My diagnostic plan was simple: I wanted to perform a running vacuum test with a pressure transducer in the intake manifold and a transducer in the exhaust to confirm a sticking valve on cylinder #2. I would then sell the shop on pulling the intake and cleaning the valves, sounded simple to me anyway. The results were not what I expected. With the scope set on a slow timebase I ran the engine at idle and waited to see a disturbance in the pattern. Both a running vacuum waveform and a tailpipe pressure waveform should be a series of similar pulses with four pulses for each 4-stroke cycle. With my Pico scope connected to the cylinder #1 ignition coil trigger signal, the Pico WPS500 pressure transducer connected to the intake manifold and a Sen-X Technologies 1^st Look transducer in the tailpipe I should see a pattern like the one in Figure 2 when no misfire is present. I will note here that there is software filtering applied to both pressure transducer channels to make the pattern easier to view.

Figure 2 - Pico scope pattern with engine idling and no misfire present. The middle waveform is intake vacuum and the top waveform is exhaust pressure pulses.

Soon I began to see irregularities in the exhaust pattern as seen in Figure 3. The arrows indicate where the pattern will be zoomed into for a closer look in Figure 4. While the exhaust pattern indicates a misfire, there is no upward pulse in the vacuum pattern that would indicate pressure pushing back into the intake manifold if the intake valve stuck open or the valve leaked across its seat.

Figure 3 - The upper exhaust pressure waveform that shows an issue at the areas with the arrows present.

Figure 4 - There is a disturbance/pulse seen in the exhaust pattern, but no problem seen in the intake vacuum pattern which seems to eliminate a sticking intake valve. The popping noise was heard during this capture.

While my initial theory does not seem to hold water at this point, the noise from the engine was driving my diagnostics toward a mechanical problem. I continued to perform many more engine mechanical tests including cranking current and vacuum waveforms and some in-cylinder tests on cylinders #2 and #3. One cranking test is seen in Figures 5 and 6, both the whole test and a zoomed in portion. After careful analysis of many waveform captures, I did not uncover a single problem on any waveforms other than the misfire indication in the exhaust waveforms. At this point all I can say for sure is that the engine appears to be mechanically sound.

Figure 5 - This 15 second cranking current and vacuum test is textbook perfect. No problems are present.

Figure 6 - This zoomed in view shows very consistent vacuum pulls and compression peaks in each waveform.

After deciding the problem is not mechanical in nature, I began to shift my focus to other potential problems. The scan tool can perform two different fuel injector tests, an automated pressure balance test and a user-controlled injector kill test. The automated test actually increases each injectors on-time and the ECM measures the rail pressure change with the rail pressure sensor. The engine will misfire during this test due to an over-rich mixture in the cylinder. This test produced consistent normal results as seen in Figure 7.

Figure 7 - This is a screenshot from a Snap-on Ethos of the automated injector balance test. The displayed pressure drops are very even. I have not seen printed specs for pressure variation for this test but over 2PSI would be suspect in my opinion.

After seeing very even injector pressure drops, I began to wonder if the spray pattern from these GDI injectors could be a problem. Using the scope and scan tool I decided to scope upstream oxygen sensor operation while I used the scan tool to shut off each injector. I expected each time I turned off one injector to see a flat-line on the oxygen sensor voltage. The actual test results were not quite what I expected to see. The scope capture is seen in Figure 8. As the callouts show, when the injectors for cylinders #1 and #4 are turned off the oxygen sensor voltage flatlines low confirming no fuel was delivered to the cylinder. But when cylinder #2 injector is off, there is greater voltage from the oxygen sensor and cylinder #3 is even higher. I was not sure how this could be and wondered if there was some leakage from the injectors or if there is residual fuel reaching the intake manifold from possibly the purge control solenoid. I decided to tell the shop I would like to replace all four injectors, and they said it was OK to do so.

Because a complete set of injectors were not in stock at any of my suppliers, there would be a delay in proceeding with the repair. This gave me time to ponder the tests I had done so far and look at each test in deeper detail. While I looked at this scope capture something unusual was noticed. This engine uses a conventional oxygen sensor, not an air/fuel sensor, and while the range of sensor voltage output is normal at about 900 millivolts, the sensor voltage is switching between 2.1 to 3.1 volts, which is a large offset from ground. I was not aware if GM was supplying a bias voltage to the oxygen sensor signal, but after doing some research after the repair was completed, I found out that the oxygen sensor signal is offset from ground on this computer by 1 volt. I will pay more attention to this in the future. When I looked back at some of my earlier captures, I also noticed the #1 coil trigger signal was offset from ground on my scope.

Figure 8 - Scope capture of oxygen sensor voltage while turning off each injector. The scope time-base is very slow, 10 seconds per division. The green pattern is the #2 injector control side voltage so you can see when that injector was turned off.

I decided to scope a computer controlled, 12-volt solenoid to see if there was a voltage drop on the ground side of the computer. I scoped the canister purge solenoid and #1 coil trigger and saw both signals were offset 600 – 700 millivolts off ground as seen in Figure 9. There has to be a ground problem on this vehicle!

Figure 9 - This scope capture of the #1 coil trigger signal and charcoal canister purge solenoid show the offset of the ground signal measured with scope cursors. The canister purge solenoid ground level is 700 millivolts above battery ground.

After consulting a wiring diagram, I saw the engine computer was grounded through both the X2 and X3 connectors with a black/white wire at terminal 73 in each connector, terminating at ground location G109. Both Mitchell and ALLDATA service information showed G109 located at the rear of the cylinder head towards the driver’s side. After cleaning this ground another test was done but the ground offset remained. I realized the ground wires at the terminal I cleaned did not have a white trace and knew there must be another ground location. After looking the vehicle up on the General Motors service information website, I found the correct G109 location. The ground I had cleaned was G112, ground G109 is on the front of the block behind the A/C compressor. Figure 10 shows the two ECM connectors, and Figure 11 shows the GM service information ground location illustration.

Figure 10 - ECM connectors X2 and X3 with the ground wires identified.

Figure 11 - Illustration from GMSI showing correct location of G109 ground. The callout in the upper right shows G112 which was labeled G109 in Mitchell and ALLDATA.

When I accessed the G109 ground, I noticed first of all that the bolt was not very tight and also some sort of shrink wrap sealer had oozed out onto the ring terminal. Figure 12 shows what the ground looked like before cleaning.

Figure 12 - The sealer for the wire shrink wrap can be seen on the ring terminal of G109. This was cleaned off and the bolt tightened securely.

After cleaning and tightening the ground wire, the scope test was repeated and of course the ground offset was gone. Figure 13 shows the ground levels for both cylinder #1 and #2 coil trigger signals and the ECM ground wire terminal 73 on the X3 connector. All ground levels are below 50 millivolts. The more amazing fact is the misfire and popping noise are gone as well!

Figure 13 - This scope capture shows all three waveforms have under 50 millivolt ground offsets.

I decided to repeat the injector kill test while monitoring the oxygen sensor voltage and found the results were quite different from the first time. This time the oxygen sensor flat-lined each time the injector was turned off and the oxygen sensor swung between 1-2 volts.

Figure 14 - Scope capture showing oxygen sensor during injector shut-off. The green trace is injector #1 control signal. Injectors were turned off in order, 1, 2, 3 then 4. The purple trace in the background is coil #2 trigger signal.

The vehicle is fixed and not a single part was replaced. The order I placed for the injectors was cancelled and the shop informed that the Captiva was repaired. There were some other items I noticed after the repair that were now looking more normal. I had noticed that the load PID on the scan tool was about 47 percent at idle before the ground repair and the load now showed 23 percent at idle. I had graphed spark timing during the initial scan test and the timing moved between 1 degree BTDC to 6 degrees ATDC, which I thought odd at the time. The timing now stayed around 11 degrees BTDC. The ground problem clearly seemed to cause the ECM to incorrectly control or calculate several functions for engine control. Although I am not totally clear on what caused the engine to misfire and why the popping sound occurred, I do know for sure the Captiva is fixed. This vehicle was a really important lesson on just how important good power and ground circuits are to late-model engine control systems. This case study also reinforced the fact to me that I cannot make a car have a problem that I want it to have, you must trust your tests and follow a logical diagnostic process to flush out the “weird” problems. Keep an open mind and try not to fall into the rabbit hole during a tough diagnosis.

Article Details

Mon, 12/02/2019 (All day)

Scot Manna

<p>Misfires are among the most common drivability issues we deal with. GDI misfires, though, add new dimensions to this common malady.</p>

<p>Chevrolet Captiva, auto repair, drivability, GDI misfire,</p>

During the initial diagnosis of this customer's concern, the original technician could hear compression leaking from the vehicle when the engine was running. At first, he suspected an injector seal to be leaking, creating a density misfire. A smoke machine was used in the cylinder to identify a potential compression leak external to the cylinder. After the smoke machine was hooked up, smoke was present in the intake manifold on TDC compression. A mechanical problem was now suspected but being a GDI engine, this test was not conclusive enough to rule out a carbon build-up issue. The customer authorized the shop to tear the intake manifold off to identify the potential problem. Before the tear down was done, I suggested we prove another way what the other technician was seeing with the smoke machine. These tests and analysis were performed in order to prove what was wrong with this vehicle before expensive tear down was done.

Get a routine, follow your routine and back your diagnosis

As a technician that works on a lot of vehicles that have been to multiple shops, I have to stay centered on my diagnostic routine. Being centered on a routine first means we need to have one. As I have grown stronger in my diagnostic strategies, it has helped me funnel my testing in a way that is logical and produces results. Earlier in my career I simply started with eliminating possibilities until the answer was found.

While deductive logic is the foundation of how we all work it should not be the sole method. Strategy based diagnostics start with the scan tool more often than not. This article isn’t based on scan data strategy but that is where this diagnosis started. Currently I am funneling my testing methods so every test is justified by the previous test’s results. My very first tests are going to start with the easiest and least time consuming to rule out the most possibilities. When it comes to a misfire, the scan tool can offer a big funnel when it comes to weeding out fuel, ignition or mechanical issues.

Once I have made a conclusion that this is likely a mechanical problem, I will stop testing for ignition and fuel and focus on what the data has led me to believe too far.

Starting my routine

I’m constantly learning new techniques to better understand/diagnose the systems that I’m working with. Luckily for misfire concerns I think there is a fundamental first test that we all should think about using to gain a direction as to what our next test should be. This first test for me is secondary or primary ignition analysis. Secondary and primary ignition analysis has not changed much since scopes were first used on the internal combustion gasoline engine. Certainly obtaining these waveforms has gotten a little more difficult over the years with the invention of the COP coil and transistorized coil packs.

Getting a pattern on a COP coil can be a challenge. A COP paddle probe helps!

However, the fundamentals of how ignition systems work is the same. Power and ground is provided to a primary coil with few windings. Once the ground side is released, the collapsing magnetic field surrounding the primary coil is induced into the secondary windings. Since there are more windings in the secondary coil, voltage is increased significantly. Now a high voltage in the secondary winding follows the easiest path to ground which we all hope is in the combustion chamber near TDC compression.

Utilizing ignition waveforms allows a technician to look at compression spark and fuel all in the same test. This gives us the quickest and best diagnostic direction for additional tests. i say direction because like I stated earlier in the article I’m not willing to condemn any one part/parts off of one test. I’m going to use my results from the secondary pattern to make a hypothesis on what is going on and what my next test should be. So I grab my newly purchased COP wand and start looking at this misfiring vehicle. As I go down the line of coils the pattern on cylinder 2 has a repeatable event in the waveform at park idle no load (Figure 1).

Figure 1

Making a hypothesis to funnel future tests

Performing secondary analysis is tricky sometimes. You really have to trust your equipment and hope what you’re seeing isn’t noise from a multitude of other contributors. One of the best ways to trust your pattern is to get primary ignition. With primary ignition you are essentially hard wired into the primary circuit. You can trust that what you’re seeing is true. However, we don’t always have the time or ability to get there with transistorized cop designs. If we are going to use secondary for analysis, get to know the good cylinders first before going after the one you suspect to be bad.

As we look at the pattern (Figure 1), we see the point of primary turn on. We see some coil oscillations and then a rise in voltage in a triangular shape to the point where primary turns off. When the primary driver is released that is where the secondary current flow begins. We have a firing line and then a burn line. As voltage continues across the plug we see little blips /rise in voltage. This can happen because of the presence of turbulence.

When at idle the combustion chamber is rather stabilized compared to high load/high cylinder volumes. When we see this sort of behavior at idle we can draw some conclusions as to where our next testing should go. In order to make these oscillations in the burn line there needs to be movement or airflow across the spark plug. When a cylinder is sealed, the volume is being condensed but it is not blasting past the spark plug because it has nowhere to flow. When you have an existing path for the movement of air - such as a leak - then it can interact with the electron field and create higher resistance for the path of ground momentarily. If the voltage goes up and down like this it means that the energy to cross the gap is going up and down. The spark is quite literally getting blown apart. This type of analysis needs to be done at park idle no load. It also should be a repeatable pattern with a dead misfire like I have.  As of right now I’m starting to suspect a sealing issue with the valve train. This test does not identify what is leaking in the cylinder but it does provide me with a direction for additional testing.

Backing up my hypothesis another way

I think at this point my number two cylinder has a problem with the inability to seal compression due to an audible noise and a secondary ignition pattern. But I still do not know what or where the leak is with definitive results. One of the ways I can back up my leak hypothesis a second way is to perform an in-cylinder cranking and running compression test with an in-cylinder pressure transducer. So I remove the number two spark plug and crank the engine over with fuel disabled (Figure 2).

Figure 2

In this waveform, you can see very low compression of the vertical column to the left. Arrow #1 indicates about 18psi of cranking compression. We see a leaning tower and non-symmetrical expansion stroke. Arrow #2 provides us with a blip on the expansion stroke. I have seen abnormalities in the expansion stroke multiple times when there is a problem in the valve train such as a broken spring or loose rocker. Arrow #3 shows a very deep expansion pocket. The deep expansion pocket tells me there is likely a leak in the cylinder.

Using an in-cylinder pressure transducer allows you to "see" changes in combustion chamber pressure and help isolate the reason for the loss.

So as we see in the waveform we have low compression because it leaked out. We also draw a deep vacuum because there is less volume in the cylinder than when we started the stroke. At arrow #4, we see on the intake stroke two brief pulses down and a consistent curve downwards on the intake stroke. The curve shape indicates a cylinder's in ability to fill. The short pulses down indicate potentially a late intake valve opening or a restriction to fill the combustion chamber on the intake side.

Proving where the leak is

I know beyond a reasonable doubt there is leak in the cylinder. I can show this to the customer visually two different ways and back up my previous hypothesis. I believe that there is something going on with the intake valve leaking and potentially not opening. Another way to prove where the leak is located is to perform a running compression test. This test does not always yield the results I need but in this case it did. During a running compression test and depending on where the leak is, I may have to manipulate the rpms, doing a snap WOT test or a decel from higher rpms.

This leak was present in the waveform at park idle no load (Figure 3).

Figure 3

Arrows #1 and #2 in Figure 3 show the expansion pocket and intake pocket. There is substantial difference in the level of vacuum on both sides. On most engines, these pockets should be similar in the level of vacuum if not identical. These pockets can differ from engine design and variable valve lift. However, on this engine they should match. But what does this difference in level of vacuum indicate?

Testing running crankcase vacuum is best if you can access a centrally located vacuum source.

One way I was taught to analyze this difference is by thinking about what is attached to each port of the engine. On the exhaust side, atmospheric pressure is present but on the intake side, manifold vacuum is present. When the piston is stroking downwards in the cylinder and a leak is present on the exhaust valve, this can siphon atmospheric pressure into the cylinder and create a less deep expansion pocket. What we see here is almost 23inhg on the expansion pocket. This value is above normal vacuum on the expansion pocket. What we can infer from this level is that the intake valve is likely leaking. If a piston is on its way down and an intake valve leaks we can add expansion pocket vacuum and intake manifold vacuum together which creates a more deep pocket. Adding this running compression waveform into my strategy helps me solidify that the intake valve is compromised.

My final hypothesis of an intake valve leak

My final test is a harder test on this engine unless you have made some special tools. Additionally, intake waveform analysis is quite tricky without the use of overlays and a lot of training. I performed this test in a way that makes it the easiest for me to understand.

When performing a cranking vacuum test you want to position the transducer in a central vacuum port. The design of the intake and exhaust for that matter can alter your data. The next best test to verify a grossly leaking intake valve is to perform a cranking vacuum test with an ignition sync. In the next test, I gain access to a central port on the intake manifold, disable fuel and sync up to an ignition event and analyze the vacuum pulls in the manifold (Figure 4).

Figure 4

I have identified each intake pull with arrows corresponding to each intake stroke. We find cylinder 2's intake stroke 360 degrees and to the right of the 360-degree ruler. After that point, we can input the firing order and follow each pull. The most significant analysis that can quickly be made it looking what happens near TDC compression on cylinder 2. Since the ignition event is close to TDC and we have chosen to sync on our affected cylinder, a rise in intake manifold pressure near TDC confirms that there is compression leaking into the intake manifold. Typically, when doing this analysis it is helpful to also have a relative compression test in the same capture. This allows the user to focus on which cylinder is low on compression and compare it to the intake pulls. Typically, a sync is chosen off cylinder 1 but it isn’t necessary. Picking the sync off of the cylinder that has the problem quickly identified where the leak was. Since we already know what cylinder is low on compression, a relative compression capture wasn’t necessary to identify the fault.

Summary of analysis

The first test with the secondary ignition analysis matched what I found with the last test, that there is a leak. The last test and the second to last test accurately identified which valve was leaking and backed each other up accordingly. The tear down on the intake ultimately identifies why we see what we see.

Figure 5

The tear down

The technician working on the vehicle removed the intake manifold and the engine was cranked over. As compression blew past my face from the stuck open intake valve I knew we found the problem (Figure 5). Only one of the intake valves is opening and the other one is seized in the head and has a broken valve spring and the rocker is off the valve and lifter. I imagine the intake valve stuck due to carbon build up, over working the valve spring till it broke. The piston probably hammered the intake valve into the head and therefore probably causing substantial damage to the valve seat. Weirdly enough after the valve cover was also removed the intake rocker is missing entirely from the engine. We managed to find most of the valve spring and one keeper still laying in the head. Does this need an engine? Maybe we can get away with a cylinder head but who knows what happened to the piston and cylinder walls. The customer declined to fix this vehicle. We were able to give him visual test results that confirm that the high dollar repair is needed. If you structure your tests to give you the best value out of your time you can find the problem faster, easier and more accurately more times than not.

Article Details

Mon, 12/02/2019 (All day)

Timothy Jones

<p>Making the judgement on a high dollar repair requires being accurate the first time.</p>

<p>drivability, diagnostics, repair, tests, automotive,</p>

TBC Corporation (TBC), one of the nation’s largest marketers of automotive services and replacement tires, is pleased to recognize 2019 ASE Technicians of the Year from NTB, Tire Kingdom, Midas and Big O Tires.
 
Every year the National Institute for Automotive Service Excellence (ASE) selects technicians based on specific criteria including ASE certification level, commitment to total customer satisfaction and community involvement. Fifty-three automotive professionals, out of more than 250,000 ASE certified professionals, were recognized in mid-November at the fall Board of Governors meeting of the National Institute for Automotive Service Excellence held at the Arizona Grand Resort and Spa in Phoenix, Arizona.  
 
“To be recognized by the National Institute for Automotive Service Excellence as a Technician of the Year is truly an honor,” said Erik R. Olsen, President & CEO, TBC Corporation. “Industry leaders who consistently demonstrate a commitment to excellence through their involvement in the community, their daily interactions with team members and customers, and their devotion to furthering their skills and abilities deserve to be recognized and celebrated. We’re very proud of TBC associates and team members of Midas and Big O Tires franchisees for their commitment to excellence and their recent recognition in the automotive aftermarket industry.”
 
Congratulations to:
Tim Creech Jr., Williamsburg, VA, NTB Tire & Service Centers
Chuck Haddad, Cuyahoga Falls, OH, NTB Tire & Service Centers
Christopher Doyle, Jacksonville, FL, Tire Kingdom Service Centers
Christopher George Jost, Boulder, CO, Big O Tires
Dave Newman, Pittsburgh, PA, Midas

Article Details

Mon, 12/02/2019 (All day)

MOTOR AGE Wire Reports

<p>TBC Corporation (TBC), one of the nation&rsquo;s largest marketers of automotive services and replacement tires, is pleased to recognize 2019 ASE Technicians of the Year from NTB, Tire Kingdom, Midas and Big O Tires.</p>

<p>TBC brands, ASE Technician of the Year</p>

Red Line Synthetic Oil, a designer and manufacturer of high-performance lubricants and additives, is known for its wide range of products. The company offers products for nearly every application possible and has recently expanded this line by offering its MT-85 75W85 GL-4 and 75W85 GL-5 gear oils. Both are designed to provide optimal gear and synchro protection for specific applications.

 p.p1 {margin: 0.0px 0.0px 0.0px 0.0px; text-align: justify; font: 11.0px Helvetica} span.s1 {font-kerning: none} Red Line’s 75W85 GL-5 Gear Oil contains the extreme pressure additives necessary for ultimate protection in street, off-road and racing vehicles. It contains friction modifiers for proper limited-slip operation across the temperature range. This oil is popularly used and often recommended by the manufacturer in many late model BMW, Dodge, Focus RS, Jeep, Mercedes-Benz, Toyota light truck and Lexus differentials and transfer cases. Engineered to provide the highest degree of protection along with longer drain intervals, Red Line’s 75W85 GL-5 is rapidly becoming a go-to product among enthusiasts when the maintenance guide calls for 75W85.
 
Since most GL-5 gear oils for differentials are too slippery for manual transmissions, Red Line offers the MT-85 75W85 GL-4 Gear Oil to ensure proper shifting while providing ultimate wear protection. This product is recommended for the Nissan 350Z, 370Z, most Maxima, Altima and Sentra models, the Mitsubishi Evolution, as well as Hyundai, Kia and Quaife synchro manual transaxle applications and NV4500 transmission used in Dodge, Chevrolet/GMC transmissions, among others. The oil offers quicker shifts and reduces the notchy shifter feeling, even when cold. A perfect synchronizer coefficient of friction helps to prolong synchro life.
 
For those who demand the best protection, Red Line’s 75W85 gear oils are made in the USA and proven to perform. Both are available in quarts for $17.49 and gallons for $71.95 at www.redlineoil.com or from a Red Line Synthetic Oil dealer near you.
 
 

Article Details

Thu, 12/05/2019 (All day)

MOTOR AGE Wire Reports

<p>Red Line Synthetic Oil, a designer and manufacturer of high-performance lubricants and additives, is known for its wide range of products. The company offers products for nearly every application possible and has recently expanded this line by offering its MT-85 75W85 GL-4 and 75W85 GL-5 gear oils.</p>

<p>Red Line Synthetic Oil, gear oils</p>

Motor Age, the nation’s leading publication targeting the automotive service repair community, and sister publication Professional Tool & Equipment News (PTEN), are partnering with Technicians Service Training (TST), a not-for-profit group dedicated to providing quality automotive repair training and educational materials at a reasonable price, on a new series of training events designed to help vehicle repair professionals keep pace with changing automotive technology.

“We can’t think of a better partner than TST to help us advance service professionals’ repair knowledge,” said Pete Meier, Motor Age’s Director of Training. “We’re providing some fantastic training that should raise the level of service knowledge for technicians who are struggling with things like diagnostics or electrical issues on today’s vehicles. These events should help them take that next step to better serve their customers.”

The inaugural Commitment to Training Live one-day event will take place May 9, 2020, at the Embassy Suites by Hilton Chicago in Rosemont, Ill., and will feature a full day of technical training courses for automotive technicians. Attendees also will have a chance to meet with suppliers to see the latest products and services available for repair shop owners and technicians.

“Events like these, and our annual TST Big Event, are crucial for our industry,” said G. Jerry Truglia, Founder and President of Technicians Service Training. “Today’s cars are more technologically advanced than the vehicles we serviced even five years ago. The amount of repair knowledge a tech needs is incredible. This partnership with market leaders like Motor Age and PTEN gives us a great platform to reach more technicians who want to stay current with today’s technology in order to remain competitive in the market.”

Publisher Kylie Hirko noted the value of PTEN’s the new relationship with Motor Age and the benefits this type of event partnership brings to technicians nationwide.

“PTEN is excited to partner with Motor Age and TST on the Commitment to Training program. Earlier this year, PTEN & Motor Age combined forces to better serve our readers and provide them with valuable training opportunities,” said Hirko. “Vehicle technology and tool technology are evolving at such a rapid rate, the need for technician training is more important than ever. We’re proud to work with industry-respected instructors like G Truglia and Pete Meier, to offer techs a high-quality, low-cost training option, that can help make a big difference in their future.”

Course details will be announced shortly, along with registration information, sponsorship opportunities and hotel accommodations. Vendor tables are limited. Suppliers interested in participating can email Pete Meier (Pete.Meier@ubm.com) or G. Truglia (gt@tstseminars.org).

ABOUT MOTOR AGE/PTEN/ENDEAVOR BUSINESS MEDIA
Motor Age and PTEN are part of the Endeavor Business Media Transportation Group, the leading provider of integrated media solutions to the automotive aftermarket and collision repair industry. With a multi-platform approach and a dynamic, wide-reaching portfolio of B2B brands and products, the Transportation Group provides unrivaled industry news coverage, product information, nationally recognized training resources and a vast e-media network. Brands include — American Trucker, Aftermarket Business World, Auto Body Repair Network (ABRN), Bulk Transporter, Fleet Maintenance, Fleet Owner, HD Pickup & Van, Mass Transit, Motor Age, Professional Distributor, Professional Tool & Equipment News (PTEN), Refrigerated Transporter, The School Bus Summit, The Transit Bus Summit, The Trucking Summit, Trailer Body Builders and the web portals SearchAutoParts.com and VehicleServicePros.com.

Headquartered in Nashville, TN, Endeavor Business Media, LLC was formed in late 2017 to acquire and operate trade publications, websites and events. The company targets B2B audiences in the accounting, aviation, dental, facilities maintenance, fire & public safety, industrial, technology, medical, oil & gas, public services, security, construction, vehicle repair, vending, and water & wastewater market. The company has offices in Nashville, Tennessee; Tulsa, Oklahoma; Nashua, New Hampshire; Birmingham, Alabama; Sarasota, Florida; Skokie, Illinois; Fort Atkinson, Wisconsin; Akron, Ohio and Santa Barbara, California. For more information, visit www.endeavorbusinessmedia.com

ABOUT TECHNICIANS SERVICE TRAINING (TST)
Technicians Service Training (TST) was spun off from the Society of Automotive Engineers (SAE) automotive technician service group, Service Technicians Society (STS). When SAE shut down their affiliate STS, "G" Jerry Truglia felt there was a void in providing information to technicians for a

reasonable price. G and former STS board member Pierre Respaut shared a common interest in keeping technicians updated on today’s technology. They formed TST, a non-for-profit organization, to help fellow technicians and shop owners by sharing their knowledge.

TST, which produces an annual daylong training program called the “Big Event,” is a 501(c)(3) educational not-for-profit devoted to the following since its inception:

• ​Keeping our fellow technicians up to date with the latest technology.
• Providing quality training seminars and educational materials at a reasonable price.
• Delivering practical, useful repair information.
• Keeping technicians informed of industry trends.

Article Details

Thu, 12/19/2019 (All day)

Motor Age Staff

<p><em>Motor Age</em> and sister publication <em>Professional Tool &amp; Equipment News</em> (PTEN) are partnering with Technicians Service Training (TST) on a new series of training events designed to help vehicle repair professionals keep pace with changing automotive technology.</p>

<p>Motor Age, Technicians Service Training, TST, Commitment to Training Live Events</p>