Originally Posted by pizzaguy

Pin 78 Do you mean pin 8?

From what I am reading, you have 12 volts at the BCM pin 49 and 8.5 volts at the switch pin 8.
Do I have that right? ………(Yes)

I'd bet if you press "UNLOCK" that the voltage at pin 8 will go to Zero like is should, and at pin 49 it won't drop, it will stay at 12………… (correct. But it stays at 12 unlock or lock)
This would indicate the wire itself is partly open, that is, resistive. This would lead me to question the crimp on the wire BCM pin 49 or the crimp on the wire at pin 8 of the switch……….(I will check tomorrow)