Gafarmboy asked me for this info in another thread that I posted on. I thought it may be good info to post in a seperate thread rather than hijack the other one too badly.Here's part of the write up,,,, there are more suggestions and easier to do type tips somewhere, I'll find those and post here too when I locate them. Someone else had discovered how to perform the below fix without taking the whole unit out of the door. There's waaay too many people buying the complete actuator from Ford at a high cost, when it's a simple resistor/fuse causing the problem....there were some guys worried about frying the wiring system, but the guys I had talked with had been using this fix for a couple years with out any issues.... A few guys removed the stock resistor and soldered in a Radio Shack replacement resistor. Ford knows this is a problem with the 2000-2001 model SD's but will not do anything about it that I have heard of,,, short of replacement at your cost with the same faulty unit.
I also found a replacement lock actuator for less than 6 bucks!!!! Several guys are replacing the stockers with this cheap but seemingly reliable replacement unit with a lot of success.....see link below
---This is info from another person,,that I have pasted here.-- Russ
To get your PSD doorlocks to work again WITHOUT spending a dime.
There has been discussions about possible issues and that the majority of us are seeing actuator motor problems and not relays, switches etc. Ill start by saying the problem is that when you hit the switch, the locks attempt to move and after repeated attempts, the signal appears to get weaker and weaker until nothing....seems like a relay or switch.....not the case at all.
If you test the signal at the harness plug to the actuator, its good. No issues here. Now if you completely removed the actuator/lock mechanism and bench test them with 12V heres what you will find. The actuator will act the same as when in the truck. Here's where it gets tricky. These things are built so that they are not serviceable, but they will comes apart relatively easily and can be put back together once apart.
First, drill out the two small rivets and then pry the case apart. As you pry the case apart you'll notice these small little plastic rods protrude up through the case cover. These rods are then "mushroomed" with heat through the upper case and then sealed with some kind of silicone. When you pry apart the case the "mushroom" head breaks off and the rod remains. You can dig out the silicone and mushroom head with a pick. It comes out very easy. Inside you will find a very small motor and some gear mechanism. Inside of the plastic brush housing, you'll find a small, thin rectangular thermal resistor relay, thingamabob - I'm not sure what its called. This little part is what keeps you from burning up the motor, should you continue to press the switch once the lock has been actuated. This thingamabob wears out over time and will not allow enough signal to get through to the motor to make it work.
THE FIX. Take a small piece of aluminum foil and wrap the "thingamabob". voila! Perfectly working motor!
To reasemble it: you cannot glue the unit together as there is a rubber gasket around the perimeter of the case and if you tried to glue the rods into the case, you would not have enough pressure on the two halves of the case to keep the gears in place (these things actually apply a great deal of torque on the case). So what you can do is break off the plastic rods flush with the bottom side of the case and then drill out the bottom case and screw it together. You'll need screws that are the same diameter as the holes in the top of the case to keep it alinged. The screws should not protrude through the back of the unit as some of the mechanism has some pretty close tolerances and a screw sticking through the back would get in the way of these mechanism - this can be remedied with a decent set of wire dikes or a hacksaw. Give it a try, its easier than it may sound!