Power Lock Issue
 

My drivers side rear door unlocks with switch and key fob but will not lock. I have to physically lock the door with the pull knob. Is this a normal problem? What does it take to fix it? 2006 Dodge 3500.

I'm no help, but your not alone. My 2005-2500 is doing pretty much the same thing, although i'm now to full manual lock/unlock mode.

sound like your Door Lock Actuator is messed up

The little motors get weak I got a similar problem with my explorer will lock but not unlock the drivers door is completely shot and I think ford want around $100 each for them!