I'm running a 4L60e with a 3200 Circle D Stall. I had to have it rebuilt in december due to it losing 3rd gear. After the rebuild it was working and performing great and then yesterday it started having issues with overdrive. The torque converter keeps slipping in and out of lock up every 3 to 5 seconds at highway speeds. I took my truck to the tuner to have him mess with it on his lap top which showed it locking and unlocking. Is it possible that the new trans is shot already. I would assume the converter is okay since its trying to lock up and its set to lock up in 4th. But if 4th were gone would that cause this?

 

The PCM is supposed to command the converter to unlock in fourth gear when you let off the throttle. It will then re-lock after getting back into the throttle. With converters that have higher stall speeds this is a lot more noticeable. Does the unlocking correspond with lifting off the throttle?

 

More importantly was the PCM commanding the unlock or not?

 

Everything with the pcm seems to be working fine. My tuner messed with the lockup and duty cycles yesterday which didn't really do any good. But I took my truck for a drive today and I was able to run it up to forth gear WOT in the middle of nowhere it went into 4th and started free revving so no more 4th gear. Guess its time to start putting away cash for a new trans and stall.