GMC Troubleshooting Questions? Ask a Mechanic for Answers
I have seen a lot of issues with the under hood fuse box. unclip it turn it over unplug connections and spray with contact cleaner and then lube with silicone. the contacts get oxidized cause high resistance and cause modules not to shut down and kill the battery. Have you had a bunch of rain as of late?
If you are unable to remove the fuse box try wiggling the harness that runs below the box enough to jiggle the contacts may help.
I must be off to work in a few and will return this evening. I will check in through out the day as much as I can.
By chance do you have an aftermarket remote start or alarm installed?
she will roll out of the tray with the wiring good luck I will check back. Thanks.
sounds as if could be bcm related you can try to disconnect both battery cables and touch them together for a few minutes this will drain the onboard batteries inside the modules and kinda do a ctrl/alt/del. may reset the odules or force them to do a relearn good luck I will do some reading tonite may be tough to guess with scan tool data., possible ign. switch issue not powering properly on certain legs.
Any new news?
Sounds like you have had no luck sorry I could not have been more help some things are just to hard to guess over the net. Cars these days we rely so much on scan tool data for diagnostics when these bugs show up we are limited to what to recommend. Just think is there anything that happened or changed, added?