I fixed all four PDL actuators with the aluminum foil and they went from working occasionally to working every time. Then I replaced the GEM (bolted to the back off the fuse block under the dash by the drivers left knee)because the wipers, door locks, 4X4 etc. was not working reliably (planned obsolescence by Ford!), now the AC will only blow out the defrosters and the door locks all stopped working at the same time. My research has led me to there being a vacuum leak causing the vent problem, Fords are famous for this for 20 years (hmm wonder why they are on the verge of bankruptsy).

To the point: I found information for a VSM, or Vehicle Security Module. This is the module that controls the door locks and it's located behind the dash on the passenger side, either behind the glove compartment or around the radio area. Ford moved it several times. I'm also pulling all the door switches out and cleaning them as a bad connection will cause this problem. There are three separate relays for these also; 1 to unlock drivers door, one to unlock all doors, and one to lock all doors. The VSM probably controls these?!

Ford build the best heavy duty trucks. This is the 2nd Superduty I've owned and I put 150K miles mostly loaded with heavy trailers on these trucks personally with no mechanical failures. The electronic controls and vacuum operated components on Ford trucks were designed by drunk monkeys though. American automakers must embrace the idea of making things to last as long as possible if they want to survive, this thoroughly planned nickel and dime BS as soon as the warranty expires is the path to their own destruction. If they keep this up they deserve to fail!

Sorry for the rant, I'm getting sick of buying little over priced plastic doohickeys that should NOT be failing one after another like stacked dominoes!

-David

 

dennisg I feel you! I've been trying to locate my 99 Ford F-250 super duty power door locks relay to connect up my Viper Alarm. TOO embarrassed to say how many hours online I've spent trying to find out.
From all I have found, pretty sure mine was removed by former owner/ alarm installer, given the dangling wires I found mid center dash by Flasher Relays. Eventually found 2 relays taped together inside the door after removing the panel wired into the locks.
Trying to make sense why one would remove the factory door lock relay and install it the door. (Given constant shock from open/ closing it would constantly get)
However, I am still interested to know officially where that relay was supposed to be located.
P. S. I replaced my door actuators with new and they work fine. What puzzles me is how do the door locks work, since I removed the 2 relays I found in the door wired into the door locks and reconnected all the wires back to factory specs in the door. Weirdness going on here.
Read more thread posts and it does seem that the GEM (General Control Module) in earlier Ford F-250 was replaced by the VSM (Vehicle Security Module) with mention of a CSM (Central Security Module) In all cases they are known to control the door locks and likelihood is that would be where the door lock relays would be located. You Tube and other videos show the door lock relay behind the glove box and mid dash nearby the flasher/ dome light relays.

 

Read more thread posts and it does seem that the GEM (General Control Module) in earlier Ford F-250 was replaced by the VSM (Vehicle Security Module) with mention of a CSM (Central Security Module) In all cases they are known to control the door locks and likelihood is that would be where the door lock relays would be located. You Tube and other videos show the door lock relay behind the glove box and mid dash nearby the flasher/ dome light relays.
It was meant to be edited into my prior post. Can't find where or how to delete it. sorry

 

It is under the center of the dash on the firewall. Basically behind and below the radio, but on the firewall. Why the @$^^ they put it there I cant fathom. Here is the schematic for the internals.

 

2001 F250-SD / power door locks with keyless entry feature schematic