I have a 1994 Z28 A4 which I daily drive. I had to do some tuning on trans tables a while back to improve daily driving and shifting; it has a Yank 3600 stall and the Rossler street/strip 2 4L60-E that I got a good deal on from a guy who went 6 speed. Also running on 3.73 gears.

I haven't had any issue with the car lately, but I let it sit over a 3-day weekend and then I got in it Monday to find the TCC wasn't locking at cruise speeds (I have it set to lock at 43 mph for around-town driving) and now I am running 2000+rpm to do 50 mph. We had some bad storms over the weekend but I cannot find any signs of a short or blown fuse/water damage.

Question is~ What should be the first steps to diagnosing the TCC issue when I have no codes set and no fuses blown? I have seen no signs of a bad sensor (logged and scanned in EEHack) or any misfire. I did read the data stream in EE Hack and see that the command is being sent for TCC to lock-up.

I also tried to manually enable the TCC from EEHack while driving (a passenger enabled it) and it did not lock up this way either. Can the command be blocked/ignored if there is a sensor giving bad output or is it likely a bad TCC Solenoid/Converter is done for?

I have put about 30k miles on this Converter in the last 2-3 years and I hate to lose lock-up. I had just got everything to finish a 100 shot install and HCI swap was going to be done this winter.. but this may put a damper on my plans and have to re-do the drivetrain once again.

 

Was the trans from a 94? Only a 94 4L60E will work with a 94 PCM. A 95 can be used only if the PCM is reprogrammed with the 95 pulse width modulated TCC lockup program, and a wire added to the harness. Using a 95 trans without reprogramming will burn TCC lockup clutch up.

4L60E year differences and interchanges.

 

I am not aware of it being 95 or not 95.. it has ran great for many miles without issues on lock-up after the tune. The PCM originally was EEB and I converted it to EE with exact same settings then modified it as needed.

I have logged in EEHack and I am seeing absolutely no errors but when I stream data I am seeing a few errors.

"Check Transmission Light Open Failure" = ON
"TCC Control Open Failure" = ON

but no errors? sigh. currently checking all sensors and trying to manually enable TCC to see if I hear the click. Hard to do alone, so may have to wait for my lady to get home.