If you have the Bose system in your Avy, it's probably the amplifier that is staying on, I had to wire in my own power switch so I could turn it off after I shut my Avy off, but if you're replacing the BCM I think that will solve your problem with the battery drain.I have a 02 chevy avalanche with battery drain last thing I can try is a bcm can I program it with out a computer ? I am hopein I can ....