Battery Drain/Passlock Issue
 

PLEASE HELP!!

2003 Silverado SS - 107k Miles (issues started out of the blue)

I'm having a huge parasitic draw and the I cannot find an exact answer to the issue. Battery and Alternator have been replaced and nothing has changed.

Symptoms:
Battery drains overnight, EVERY night. My steering wheel doesnt lock. My driver side seat heater does not work. If I turn the seat heater on it shuts off after 10 seconds. If the passenger seat heater is on and I turn the driver seat heater on, they will both shut off. Passlock is goofy, my steering wheel wont lock, the other day my truck would shut off right after jumping it, had to let the passlock reset. My security light has flashed at times and has been on while driving at times. I do not have a key fob, I do not have auto start. I lock my doors with the switch everytime I leave the truck. My gauges have been acting just fine, no issues, no stepper motors running while its off, no dancing needles, but it IS pulling a huge draw when off via the IPC/DIC fuse.

What I've Done:
I have tested all the fuses, I have a 700+MA draw. If I disconnect the gages it drops to 260, if I disconnect the HVAC controls it drops to 220. If I disconnect everything from the BCM it dances between 77-130-180 back and fourth constantly.

I do have subs and an aftermarket deck. we disconnected the amp and the stereo. No drop in draw from either of those.

I have nothing but assumptions as to what it can be. I took it to the dealer and the BCM is up to date as is the ECU. They did all the tests and unplugged each module individually and the guy still had no real answer as to what to do.

I have found tons of threads on this but never and answer as to what people have done to fix it, just speculation. I left my seat module unplugged thinking that maybe the seat heater was not letting the BCM go to sleep. Still had a dead battery.

someone please help, Im just throwing money away at this point.

First- you don't have a steering wheel lock.
Second, Passlock issues means your resistive key is not being recognized by the security system. usually because it is worn or because tumbler is bad.
Third, having power draw issues combined with the key issues would tend towards faulty key electrical switch and tumbler assembly.

For starters, I'd recommend unplugging the power connector (not the tiny ribbon cable with 3 wires) from the key switch and seeing what your power draw does.