You will need to remove the trim on the liftgate. You then remove the switch from the latch. There is a sensor for the glass window and the hatch. In both cases the sensor is located in the latch and held in by a single screw. The sensor has a plastic center that is crimped into the metal housing. The crimped edge gets loose after lots of use and lets the plastic portion work it's way out partially. You need to push the plastic part back in and take a pair of pliers and crimp the edge tight. If done right the white plastic plunger in the center of the sensor should be sticking out about 1/4 of an inch. Reinstall the sensor and close the door to test before putting the trim back. This will save you about $25.00 for a new part from Chrysler.
My 1998 Jeep Grand Cherokee liftgate open warning is on all the time beeping and keeping the internal lights on. I tried lubricating the latch, pulled the electrical connector off and reseated it. It still indicates open. The latch seems fine. Locks fine. I would like to fix or defeat the sensor. I pulled the sensor and tried jumping between two pins and that did nothing. Any ideas?