On my 04 Blazer the dome light goes on at random thus draining the battery. This only seems to happen in cold weather. I can't find any of the door switches to see if there is damage or alignment issues. Sometimes the "ajar" light for the gate goes on. These issues appeared after being rear ended several years ago.

 

I would look at the gate then...seems like most likely source. The harness might be grounding out. Pull the interior panel and check the wiring out would be my first guess.