Good luck with this! I had an aftermarket GPS system put in and had a dead battery every 2 days, so I spent hours upon hours tracing this problem out because the stereo shop said it wasn't their unit causing the problem. You will have to pull 1 fuse at a time to find the draw. If I remember right on the Hummer you want to be around 20-40 mA (.02-.04) to be OK. I was at 181 mA (.181) and that was a problem. I eventually found out my factory Bose amp was not shutting down. Fixed that and droped to 49 mA but still had a dead battery problem. Go to find out that the stereo shop drained my battery to dead and recharged for a bit and drained to dead again and again, so got a new battery and haven't had a problem since. Good luck!
