TCC Archives - Page 2 of 2 - Transmission Digest
V-8 Toyota Tundra

I am sure by now that most shops out there have run into the pesky P0770 “Solenoid E Fault,” on some type of Toyota or Lexus vehicle, that has given you the runaround. ATSG senior technical consultant Jim Dial and I have spoken about this on numerous occasions, since it is a very common problem on our tech line. Jim did a bit of investigating, and this is what he discovered.


As valves and bores begin to wear and allow leakage, the easiest path for the leak is to exhaust. Two things happen as a result of this wear-induced exhaust leak. First, the leak allows a pressure drop, which is loss of control pressure. Valves or components no longer move, apply or respond as intended. Second, the amount of exhausted fluid and, therefore, the amount of air entering the sump are increased. The amount of aeration can easily surpass the sump’s ability to dissipate the air before the pump picks it up. The minimal sump capacity of the 5L40-E makes it especially vulnerable to this problem.

TCC Apply

The debate about whether to use a grooved or smooth friction lining to rebuild a converter originally equipped with a grooved lining has been going on since the day grooved linings first arrived at torque-converter shops. Those advocating a grooved replacement lining always seemed to have the upper hand because they used the very strong argument that “it is the same as OE.”

Centerline Issues: TCC Frictions Bonded Off Center

For several decades the importance of the torque-converter centerline has been hammered home by Don Randolph of DACCO Inc. Don’s sentiments on this subject have been echoed by the torque-converter original-equipment manufacturers (OEMs). In fact, every OEM torque-converter print starts with a true axial centerline, which serves as the reference point for all axial measurements.

Blame the Torque Converter, Part 2

Last month, in Part I of “Blame the Torque Converter,” a 2001 Volkswagen Jetta and a 2002 Toyota Tundra were both thought to have faulty torque converters. Both vehicles had TCC-related trouble codes (the Jetta had a 740 code and the Tundra had a 770 code).

The Code that just Wouldn’t Go Away

This particular tech call was the usual 4T60-E or 4T65-E transaxle with the code P0741, “Torque Converter Clutch System Stuck Off.” It began as so many times before with the normal question, “Was this unit just rebuilt or is it coming back with this problem?” The next question was, “What repairs have you done to correct this problem?”

What a Drag

The ATSG tech line frequently receives calls related to engine stall or even a partial-stalling condition that could be easily mistaken for an engine-performance problem in 1995 and later Audi/VW vehicles with the 01M transmission.

Lockup Surge in Allison 1000s

Have you ever found yourself chasing a “phantom” TCC drivability problem in a GM vehicle that uses the Allison 1000/2000/2400 series of transmissions?

If you have, there’s a good chance that the root of your problem turned out to be the torque converter. No earth-shattering news there, but what is unique is that the problem was likely on the outside of the converter, not the inside.

Indexing TCC-Piston/Damper Assemblies to Turbines

At a recent TASC™ Force meeting, one of the members expressed concern about an increase in the number of worn-out bores in TCC pistons that he was seeing. Although the problem is prevalent in many different pistons, his main focus was on the GM 298mm pistons.

TCC Apply Piston & Cover Deflection

A 604 transmission with a 740 code led to many different approaches and attempts to troubleshoot the underlying problem. As the possible causes were narrowed down, the focus began to turn toward the converter. Replacing the converter with a factory unit eliminated the 740 code, and since the code would show up on any road test, this seemed like the perfect vehicle to identify the root cause.


The title of this article envisions scenes from that 1950s “B” sci-fi movie by the same name – only, in this instance, “THEM” refers to the original-equipment manufacturers. This month I have a few tidbits relating to problems you may have to deal with that were created by the vehicle manufacturers.