97 Jeep Gnd Cherokee showing 'rear door ajar when liftgate closed

first is diagnosis.
you examine and test it. to see if its electrical or mech. failure.
and once discovered that follow that to logical conclusions.

upper portion door

Locks should be tesed /checked via hand terminal(which dealer have).
sometimes that VIC module creates problems due to badsoldering points on its circuit board. try to resolder them. but sometimes it shows what is reads from sensors around car. like tail light out or door is ajar signals.

there is a possibility that switch checks the condition of door which is actully bad and this makes auto lock system act like door is not closed and wont allow it to be left as locked position. this is looking like a endless loop.

Hi, if the door is a little loose, try adjusting the latch in a little tighter.

Unlock the doors with the power unlock button then you have to push in on the bottom part of the plastic bezel that surrounds the liftgate handle, while at the same time pulling the liftgate handle outwards. It should open then.

Review this reference documents: ZJ-Secc-8P-Power-Door-Locks (Page 4)

Good luck... and rated my help!!!

You need to remove the panel from the liftgate and unlock and open it manually at the latch. It is not fun, but you can get the panel off with the hatch closed.

sounds like a defective liftgate latch assembly..ajar switch is part of latch..dealer item

remove the door switch, clean and reinsert. It switched ground to a black cable, which goes to the PCM.