Sorry, should have been locks in title..

I have a 2001 F150 extended cab 4x4 with power locks and remote, when I lock the doors with the remote occassionaly they will unlock right after that, also I've locked the doors and came out a few hours later and they were unlocked, this happen at several different times and places.

I finally pulled the fuse so I could keep the truck locked.

I'm trying to figure out what is wrong, I've found a wiring diagram, but not sure what I should be looking for or what could be malfuntioning.
Anybody have this problem and what did you do?
Any suggestions?

Tried a search but didn't find anything.

TIA

Al