2002 Buick Rendezvous 6 cyl All Wheel Drive Automatic 44000 miles
The door ajar warning comes on intermittently for the rear hatch. This is even when I am sure it has been closed tightly. I adjusted the striker rearward slightly which seemed to help. However, it still happens from time to time.
Near as I can tell the switch is in the rear latch assembly. Those switches will get bad spots in them and do what you describe. The door ajar switch is most likely serviceable seperatly from the latch assembly, but you may have to remove the latch to replace it.