Quote Originally Posted by nox View Post
First thing I would do is pull the halfassed work done to the wiring. Get the harness behind the dash as clean as possible. You don't have to get an OEM stereo, just undo all the crap for now. Cap the ends of all the wires you expose to prevent any crossing, aarcing etc.
Do you know if the non-bose audio used a separate amplifier as well? From the bit I've looked around, there are some [4, looks like 2 conductor] extra wires leading from above the AC control panel to behind the glove box, i suspect it is wiring to bypass a stock amp.

Quote Originally Posted by nox View Post
Check for some of your issues. If they are gone, great, if not then further teardown is needed. Are the HUD and DIC factory options on your car? If yes, great, if no then you need to dig deeper and find any modifications to the wiring. This could involve literally pulling the entire dash out.
As far as I can tell, HUD and trip computer were standard on '01 GTPs. Found a pdf spec sheet from GM. What I'm calling the DIC is the little screen that indicates doors open, boost gauge, and will cycle through Fuel Used, Range, Oil Life, and MPGs. Is DIC or trip computer the correct term for this?

Quote Originally Posted by nox View Post
Also, not for nothing, check out the BCM. If something has happened to it, it could cause many of these issues.
How would I go about checking the BCM, or is that best left to a shop? Also, I'm assuming that's the box near the onstar unit in the trunk?

Still scratching my head about the blower motor running with key off though. Gut instinct tells me a relay was bypassed, and a constant hot was used rather than keyed.