There are four different microswitches in the rear door latch. Any of them can fail. Also, the switches can be fine but the latch can stick and not activate a perfectly good switch. Both failures are common.Thanks so much for posting this video, however I followed all the directions to the T (including verifying continuity before and after replacing the microswitch) but the warning light comes on after a few times of testing the door. Weird thing is now, in the few times that it does work after resetting the doors, there is a few seconds delay between the time the door closes and the time it latches that did not used to be there before. Any idea what it could be?
If the Slide Door light is on then that means a code is stored. Use a jumper wire across the #4 and #9 pins of the DLC and then turn on the key. It should display the codes on the gauge cluster. You can then use the trip meter knob to scroll through them if there is more than one. Post the code(s) back here. Just be careful when jumping the terminals as you don't want to spread them or damage them so they don't make connection to a scan tool at a later date.