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.
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?
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.