[Entropy]

98 E150 with power locks will not work with the door buttons, however work find with the key fobb. Also other unusuall things: When you press the door lock button the inside lights (dome lights) come on and sometimes when driving down the road the locks will latch and unlach several times.

 

[Poppy]

try lubing your door locking mechanisms with a silicone spray, PBblaster or WD40 (some argue against WD40) I am guessing that the door ajar sensor is messing with the locks. The door ajar sensor sometimes gets stuck, and lubing it works.

EDIT: you may also try cleaning the door lock switches in the door panel with some electronic contact cleaner.

 

[royesses]

Also look for a broken wire inside the wiring harness belows between the door and jamb.

 

[mark v]

Yep sounds like your door lock switch. My Windstar has the same issues. I use silicone spray lubricant cause it doesnt wash off easy.

I am the one that hates WD-40, it is a good lubricant for breaking nuts and bolts loose but it washes away very easy.

I use WD-40 for lubricating nuts and bolts that are rusty that I will be removing and also for the special aftermarket air filter in my Corvette.