Understand your frustrations. I wonder, on the TAC 20, using IMS, there is a feature on a pull down menu in the diagnostic portion that'll let you run a variable time recording of all inputs and their states while running on automatic. I think it's simply called "Recorder". Once the car faults, you can go back and watch the "tape" to see which input may have blipped. Check it out. Also, there is a back up battery for the DSP. Typically right side near the bottom of the controller. Maybe not your trouble, but weak batteries in any control circuit can cause grief to the unsuspecting mechanic (KONE KMC, GEN2 and I'm sure there are more).
