Originally Posted by
Awheeler
Wanted to provide a quick resolution to this issue in case anyone else encounters the same thing. Robert is 100% correct. This is an ECM 'switch' issue in circuit 422. I did trace wires and found a few things that needed to be sorted out, but did nothing to fix the issue. Also checked every table in the tune and found nothing to fix the problem. So, I put a manual switch in line on PIN 42, the tan / black wire. Nothing fancy, just the tan / black wire to an 'on / off' switch to a ground. Went for a drive and as soon as switched to on, the TCC locked. Switched off and unlocked. Everything works perfectly except for the volts that come from circuit 422.
So, two ways to fix - 1. new ECM and 2. manual switch. I am going with option 2 for now, until I can work a few other things out before a new ECM.
Robert, thanks again for all of your patience and advice. I would have never gotten to this point without your input and suggestions.