Rob Faucett
Common Mercedes 722.9 Problems
Like most other transmission, as the years go by, the 722.9 is hitting the bench more and more often. And, over the past few years, we’ve seen some common problems among them. As usual, the simplest things can lead to major problems in the 722.9. The majority of the failures we’ve run into are caused by the O-rings on the tips of the solenoids deteriorating, leaking fluid, and not properly ...

Even Common Conditions are Sometimes Wrong
It’s easy to know the right thing to do after the problem’s fixed; it’s a little more difficult to track down the actual problem to begin with. Experience, time, and cost can sometimes lead to replacing parts that weren’t needed, wasting time, money, and reputation. Anyone who’s been building for several years can tell you all about the old 125C and their lockup solenoid problems. The...

Going Nowhere Fast... 5R55W Delayed Forward Engagement
Every transmission that comes in your door will have a problem and something that caused it. Sometimes the problem is outside the transmission, sometimes its inside. Knowing how things work will make it easier to locate the cause. A 2006 Ford Explorer with a 5R55W started having a severe delay during forward engagement once it warmed up. The customer drove it for over a month like that, until i...

Gear Ratio Codes vs Solenoid Performance Codes
You’ve no doubt heard the old saying: “Don’t judge a book by its cover.” That old saying can be revised for the modern diagnostician: “Don’t judge a code by its description.” Many code descriptions can be very misleading, and jumping to conclusions by what’s in front of you can become a costly mistake. Here’s a story about a technician who was working on an AS68RC that was dis...

More than a Scan Tool to Diagnose an Acura
Any one that knows me will tell you, I love tools. Every time the trucks pull up to the shop, it feels like Christmas. The best thing about them, they make life easier on me, and having the right tool can make the difference between getting a job out the door today, or fighting with it for a week. The fact that the best tools are very expensive, especially electronic diagnostic equipment, makes...

Understanding Pressure Switch Operation Makes Diagnosis Easier
Knowing how a transmission works is the most important part of the diagnostic process, followed closely by having the right diagnostic equipment. Scan tools can save a considerable amount of time, and, with the AS68RC, there’s enough data to diagnose almost any problem from the drivers’ seat. This transmission has several solenoids and pressure switches (figure 1). It has four linear soleno...

The Problem and the Cause
The key to repairing any problem successfully is twofold: You need to address the problem and the cause. Fix only the problem without addressing the root cause of that problem, and you can bet that the car will be back. What do we mean by “addressing the root cause”? Let’s take a look at a 6L80 with a no high gear and no lockup. The owner of the truck says the engine seems to run at highe...

Torque Converter Durability
Durability and performance have always been a concern for anyone building transmissions. The same can be said for torque converter rebuilders. Though there are many aftermarket modifications available, and some in house modifications, various little steps in the rebuilding process can make or break your rebuild. When it comes to doing it right, it’s always best to ask someone who’s successf...

Why a Graphing Meter Makes Diagnosing Intermittent Electrical Problems Easier
The advantages of having the right tools for the job can make the difference between getting it done quickly and beating your head against the wall. One tool that can make your job a lot easier is a scope or graphing meter (figure 1). Almost every job that comes through your door today will lead to some electrical diagnosis. These diagnoses can include checking the fluid level and condition, ch...

Basic Test Procedures: Isolate No Reverse on a Jatco JF506E
One of the most common problems with the Jatco JF506E transmission is when they won’t go into reverse. This can be all the time, intermittent, or only when the unit’s cold. It’d be easy to assume the problem’s something internal, so you might want to pull it out and get it on the bench. But, as most of us have learned over the years, that’s never a good idea. Before going any further,...