Cool It: What You Need to Know about Your Vehicle's Cooling System
A recent study found that up to 40% of all engine failures were a direct result of cooling system issues. As the vehicles we service continue to evolve, the coolants and systems designed to keep our transmissions and engines operating at the correct temperature are also changing. Many of the changes have led to confusion at the repair shop level. For decades, vehicles used ethylene glycol (gree...

What's Causing That Shudder? A Deep Look at a Misfire Issue
As today’s vehicles continue to become more complex, the problems we face also tend to increase in complexity. Several years ago I wrote an article about the “new direct-injected gasoline engines” that were just being introduced. Since then, most direct injected engines have added turbochargers, superchargers, variable cam timing, and now variable lift camshaft technology. Volumetric effi...

A Common Sense Approach to Charging System Diagnosis
In the previous article, we discussed the issues and operations related to the charging systems in common use today. Charging system problems may cause various vehicle issues, such as transmission shift and pressure control problems, DTCs, and driveability-related complaints. Testing the charging system is fairly straightforward if you understand how the system operates. A voltmeter, scan tool,...

High Output: A Look at Today's Charging Systems
The longer I’m around, the more I realize the importance of the basics. How many times have you tackled a complex vehicle issue, only to find the problem was something really basic? With each year’s seminars, I find that we likely have some information that deals with system powers and grounds. The more complex the system, the greater the need for a proper power supply and ground. Vehicl...

4x4 Mayhem: Diagnosing DTC C0306 for the American Axle (AAM) Transfer Case
Change happens even when you don’t realize it. Change in this industry is happening quickly and that trend will continue for several years to come. All too often, you’re expected to repair problems you’ve never seen before, often part of an unfamiliar system or component. The lack of familiarity and understanding with the system or component can be frustrating as you fight your way throug...

Can We Talk? Diagnosing a Lack of Scan Tool Communication
There are many different types of communication protocols in today’s vehicles, depending on the manufacturer and system. These include CAN, Flex CAN, UART, Keyword 2000, MOST, BEAN, LIN, LAN, CCD, UDS, Byteflight, Flexray, and PCI to name a few. If you want to repair today’s vehicles, your equipment must be capable of communicating with all of the different protocols. Developed in 1984 by B...

A Breath of Fresh Air: 8-Pin Mass Airflow Sensors
For decades, we’ve seen mass airflow sensors (MAF) on the vehicles that we service every day. Most technicians are aware of the function of the MAF sensor, but may not be fully aware of the effect a faulty MAF sensor has on engine and transmission operation. MAF sensors are used in both gas and diesel applications to measure the mass of the air entering the intake system. Many issues can deve...

There is More than One Way! Selectable One-Way Clutch Technology
The first one-way clutch was designed in 1869 for use in a bicycle. In the years since, we have seen this technology advance and now one-way clutches are used in everything from hay balers to helicopters. Several different types of one-way clutches are in use, these include: Roller designs Sprag designs Spiral designs Diode designs While one-way clutches share the same function, t...

A Look at Wiring Diagram Changes
2A lot of technicians just aren’t comfortable with the newer format that many manufacturers use to display wiring information on their a schematics. It isn’t surprising: Schematics and their formats have changed significantly over the past few years. For example, let’s look at the GM schematics and some common aftermarket applications, such as Mitchell and Alldata. Alldata and Mitchell re...

Driveability Diagnosis: It Couldn't Be That... Or Could It?
Diagnosing today’s vehicles is a challenge that every shop faces. A quick, correct diagnosis is the difference between the job being a moneymaker or a loser. Most of us have seen vehicles that weren’t only a challenge to diagnose but, in some instances, have made us wonder why we ever got into this profession. Driveability diagnosis, like transmission diagnosis, is affected by the technolog...

Looking for Information: Allison Prognostics
We’re all looking for information to help repair the vehicles we face. Often the key to a successful repair is simply a matter of experiencing the symptoms the vehicle is exhibiting or understanding the theory of operation of the system you’re dealing with. Allison transmissions are available in several speed configurations including 5-, 6-, 7-, and now a 10-speed unit known as the TC10. Ma...

Shift Time: GM’s New Electronic Shifter
An overview of GM’s ETRS system: a shift-by-wire electronic shifter that’s just begun to show up in 2017 Buicks and Cadillacs. Covers how the system works and all the idiosyncrasies you’ll need to be familiar with.

Now That Was a Good PUN - Programming and Part Numbers on 8L45/8L90 Solenoids
Changes in technology keep many of us awake at night. The constant updates and changes have an effect on everyone, even if they don’t realize it at the time. One of the more important things to consider when diagnosing today’s cars is that not all solenoids are the same. To diagnose each solenoid correctly, you first need to understand how they’re supposed to operate. The GM 8L45/8L90,...

Tackling a 4ET50 Hybrid
Many transmission technicians are hesitant to tackle hybrid and electric transmission repairs. But those repairs may not be as difficult as you might think. As with all repairs, the first time you work on a specific unit, you’ll want to be extremely careful not to make a mistake. With hybrid/electric applications, you also need to pay close attention to the safety aspects of the repair proces...

Oh No! Another Programming Failure!
Programming a vehicle is becoming part of everyday service for most shops today. More and more problems are being addressed by software updates rather than hard part replacement by all manufacturers. Like other vehicle technology, the reprogramming process continues to evolve, and with that evolution, problems with programming continue to occur. Some programming issues are “self-inflicted,”...

JR40-E With No 4th Gear
Sometimes life throws you a curve… and those curves get even tougher to hit when the last time you faced this pitcher was so long ago you have a hard time remembering what he looked like. So, when that pitcher starts throwing fastballs, you have to wonder when it’ll stop. So goes the story of a JR403-E. Many of you may not be able to remember the last time you faced one of these units; othe...

Everything You Need to Know About Torque
Sometimes it’s hard to imagine just how much technology goes into even the smallest parts in today’s vehicles. Take fasteners: Bolts, nuts, and studs are things we seldom think about, but they can cause more problems than you may realize. You see terms such as torque, torque angle, and torque to yield, but few really understand what those terms mean. How many times have you seen a broken bo...