I bought a used 2003 XLT Supercrew F150 5.4L just a couple of days ago and realized I have a problem with the door locks. Once the car is unlocked either with a key or remote the door locks will not lock again. It doesn't work with either the button on the door or on the remote. However the interesting thing is that when I start the truck and put it into drive all the doors lock, but if I were to unlock the doors they will not lock again.

So to lock the doors every time I park I have to run around locking all 4 doors. If anyone has an idea of what is going on or how I can fix it that would be great.

To me it seems as if the truck thinks that I door is open or something. Because when I try to lock it I hear the mechanisms working but they just don't go down.

So a summary of my problem again:
-once doors are unlocked they will not lock again, unless I put it into drive and move then they lock
-button on door and remote do the same thing
-seems like the mechanisms work but just don't lock (since they lock when I drive)

Thank you to anyone who can help me.

 

Dont feel bad been doing it for years lol same thing to lazy to fix it but i only have 2 locks. Door lock actuators getting weak... Possible bad relay.... etc as well as the door switch well on mine anyways but thats more of a window issue