I just brought home a 2005 1500 yesterday and the rear door doesn't open. The used car shop is ordering a new lock, but I'm not so sure now that it's the lock itself.
The FOB and the drivers door power-lock button ONLY works for the front doors. Neither will open the two back doors or the rear door. There is NO clicking to indicate that those locks are getting power. If it were just the rear door or just the two back doors, it might be easier to diagnose, but since it's all three doors that have the same symptom, I'm reaching out to advice here.

The FOB and the drivers door power-lock button WILL LOCK the rear doors, just not open them. I have to reach back and unlock those rear doors manually.

Lastly, what the Sam Dickens is this???

 

looks like stereo wiring for an amplifier and subwoofer...its not factory.


Are they replacing a rear liftgate module or a lock actuator...and for which door is the lock for?

 

They've been talking about replacing the lock in the rear door.