I have searched for this problem and have not found the answer.
I have a 2002 Screw, and all of a sudden my door locks quit locking when I start to move forward. I have run through the steps to ensure it is activated, and all locks will function with the switches, just will not auto lock when in drive and moving forward.
Any ideas?

Thanks

 

Can't help you, but I have an 02 also. Occasionally it will not autolock at 3 MPH in Drive. Sometimes I stop, put it in Neutral then back to Drive and start again, bingo it locks. I'll be interested to see the answers here from those that know.

 

I had a similar problem on my '03 Supercrew. I think I found the answer here about a year ago. You may also notice your interior and bed light on the back of your cab stay on. Try squirting some silicone spray, wd40, or some other good spray lubricant inside the edge of the doors where the locks are. Something about how Ford changed the design of those locks, and the switch to tell the truck to lock the doors. When that switch sticks the doors won't lock.