well i have had no lockup for over a year and still not sure how to fix it...i have a v8 tpi motor with a tpi"730" ecm and the truck was a 4.3 5spd....i have probed the purple wire for power on the tcc hookup and i have power there...i cut in a wire to the tan wire and ran it into the cab...at about 50-65mph i grounded it and nothin at all...ive done this twice and i get nothin...been told it could be a pressure switch GM#8642473...or a bad tcc solenoid in tranny "not sure on a part number tho" anyone else have any ideas...i need to get this fixed befor it gets to hot out again...dont want to burn up my $1400 trans any time soon!! I am runnin the bigest cooler b&m makes tho....but still....need help/info on what to do and out try thanks

 

The ground wire for the TCC solenoid is tan/black. With power off, try measuring resistance between the purple wire and tan/black wire. Expect about 25-35 ohms.

Fortunately, the TCC solenoid is accessible through the pan on the TH700-R4. It's above the filter near the front of the trans pan rail. Some transmissions had a temperature switch used to signal the ECM in the event of overheat, but that shouldn't prevent lockup by manually grounding the solenoid.