Hi -
My wife has a 2002 Chevy Tracker. A few weeks ago, the rear cab overhead light started flickering while we were driving . Bigger bumps in road seemed to cause them to flicker. We checked all the doors, and all were closed tight, with no obstructions..
Then I noticed that I could get that light to flicker by bumping the driver side door with my leg , even while idling.. So it went for another week. Now, she says the light is on full-time.
Has something shorted, or shook loose? Where do I look for the problem?

Thanks!

Could be the bulb has shaken loose, therefore the flickering problem.

Likely the door-ajar switch in the door jam has failed.
Try manipulating that door jam switch for proper operation.
If that switch isn't at fault, you will need to search for a pinched/shorted wire in that door.

Thanks,CaptainRich- couple of loose screws on the door jam that must be part of the switch assembly. One had actually fallen out! Thanks again!