I have a 2009 H3. My Hummer ran fine during the day but overnight my battery would be dead. My radio was acting up. I couldn't set clock or switch between radio to cd. The only aftermarket equipt installed was trailer light adapter. My hunch it was either the radio, onstar, amp, or trailer lights. I took the fuse out for all three before I went to bed. Next morning it cranked up fine. I put the trailer and amp fuse in but not the radio. It cranked fine all day. Anybody have problem with radio? Should I just put a aftermarket radio in or can the radio be reprogrammed?

 

Did the problem start when you put on the trailer adapter? There could be just some wiring messed up somewhere.

 

with doors closed,all off,unhook one batt terminal and check milliamp drain. it is 110 ma. normal
as you replace fuses you will see the bad circuit.

when first connected the ma meter witt go to 2 amps briefly then drop to 110.