[ls1nova71]

There really isn't any way to test a TAC module other than trying a known good one, but if your throttle is working, then the TAC is good. It doesn't get a VSS signal, that is done in the PCM, so if you weren't getting that, your transmission wouldn't shift correctly. I would still try adjusting the brake switch though. What happens is the two sets of contacts don't open and close exactly at the same time inside of it, so when you let off the brake the first set of contacts open, and the brake lights go off, not always will the second set of contacts close at the same time, so you will be sending the wrong signal to the PCM, and there is a lot of fail safe built into the cruise control.