I have this strange issue on my XJ when I use the power locks on the driver’s side, the passenger side door and rear driver door will lock and unlock just fine but not the rear passenger door. Now, if I use the power locks on the passenger side door, the situation is reversed concerning the rear doors. The driver side and the rear passenger side will lock and unlock just fine but not the rear driver side. When examining either door that isn’t properly locking or unlocking I can see the button move a little but not enough to lock or unlock the door. The rear hatch is fine in all this. Anyone know what could be going wrong?

 

There is all sorts of monkey motion between the lock button and the actual latch..these rods and linkages get rusty and corroded so they do not slide and move properly. It happens at all the doors . Its best to remove the inside liner and spray all the mechanisms with some sort of pb blaster and then move the key/automatic locks / and lock buttons until everything moves freely. If you spray in by the latch you can get to some of these parts with less trouble but its not as effective

 

It could also be in the master switch on the drivers door , I had to re-solder mine because of a similar problem , BTW all power routes through the passenger door wiring .