TCC lockup wiring

[That GN Guy]

My car has the condition where the TCC stays locked in 2-4 and I just changed the solenoid. That didn't fix it but I needed to do fluid and filter anyway. Checking pin a&f on the aldl yields 3 volts with the key on, it goes to 0 when I step on the brake pedal. Should be 12 and 0.

From my understanding I have a short somewhere but I'm not sure where to start. Wiring at the aldl, at the ECM, brake switch, or at the transmission? Any suggestions?

 

[gsgns4me]

No suggestions, but here is the electrical schematic.

https://www.vortexbuicks-etc.com/TCC.jpg

 

[That GN Guy]

No suggestions, but here is the electrical schematic.

https://www.vortexbuicks-etc.com/TCC.jpg

Thanks, that diagram is better that what I was using. Looks like my problem is on the black and tan wire from the transmission to the ALDL port. Time to get dirty

 

[salvageV6]

Unplug the connector from the transmission and re-test. The ground wire can be shorted to ground inside the transmission keeping lockup engaged at all times, the wire chafes on the metal it's attached to from the connector to the solenoid short wires inside the tranny.
Your issue is a ground on the black striped wire when it should only be grounded by the ECM.
Another test would be to unplug the big ECM connectors in case the ECM is shorted to ground at all times causing lockup at all times.
Make sure the +12 volt purple wire loses the +12 when you push down the brake pedal.