For some reason the PCM sees conditions for which it dis-allows commanding TCC lock...

the TSTATExx pids might reveal the reason(s).

 

The pin swap would be a good idea, but first we have to see why TCC lock is not being commanded (misfires are zero).

 

I'll have to browse the available pids in the am. Thanks for the input....much appreciated.

 

Have you checked your brake switch? You should be able to get it on the scanner under status bits. Also what are the dtc codes for tcc set to? Could be a diagnostic test running and disabling the lock up.

 

No, I have not checked the brake switch...I'll make sure to do that asap. Kinda sucks here right now....nothing but rain, and I HATE driving the car in the rain to do any more logging. I did log DTC's before though...and there were none triggered.

I'll check the brake switch, and report back with what I find. Thanks for the idea!

 

Any luck figuring this out? Mine acts the same way. Allows lock up but falls in and out of lock up while cruising. Haven't set mine to 100% but will tonight.

 

I'm having this same prob in a 06 silverado, It does it around 70-80 mph...

 

Has anybody found a solution for the lock/unlock issues. I have plans to do this 4l80E swap on my OBD1 LT1 Trans Am.

I'm trying to find as much info as I can before the swap.