I've been thru lots of old posts, experimented with lots of different settings, but I still have a problem.

My TCC locks at 40mph exactly in 3rd and 4th, regardless where I set the speeds in the prom. I have set the 'forced tcc lock at mph' to 200mph to negate any possiblity of that being the problem.
Funny thing is that the 'TCC Locked' flag in WinALDL comes on at the right times, corresponding to the changes i make i the prom, but the TCC is usually already locked up, back when i went thru 40mph. I have checked the wiring against the factory drawings and everything is ok. Its definately coming on as a little tap on the brake pedal releases it and its pretty easy to detect with my sloppy 2800rpm convertor.
Surely this thing doesn't have a hardcoded 40mph lockup that overrides the table parameters or something equally silly does it?
Theres a definate clue in the winaldl flag.. Its almost as tho something other than the ecm is turning it on..
Any ideas?
Ben.

 

If the trans is wired differently inside, it would do that. Some were wired so that the 3/4 switches closed and locked the converter. I believe a single wire lock up solenoid means that the switches control lockup. They just pass the current on to the self grounded solenoid.

 

Thanks for your response, but thats not the case here. It will drive in 3rd or 4th at under 40 mph unlocked, but locks as soon as it hits 40mph. Also I have the factory wiring drawing book (84 vette) and its not wired like that, the TCC is controlled by the ECM.
Ben.

 

Trace the wire down to the trans,
Its only a ground wire and see if its actually grounding (disconnected from tranny) before 40.
There is also a pressure switch that forces ground - maybe thats the problem - if so either disconnect it or try another.
The selenoid is right on the bottom of valve body, Pan off of course.
Good time to change trans oil