Power door lock issues? Here are some helpful solutions!
I recently replaced my power door lock actuators (previous owner removed one of them, the other was KIA). This info should be helpful for ~86-93 cars. It may be similar on later models too, but I can't say for sure. This work was done on an 89 LX convertible 5.0.
If you don't have a ford factory riveter, a 1/4"x1" bolt with a nylock nut will hold the bracket for the power lock perfectly. Don't tighten it all the way, I believe it needs to swivel a tad. After you get the bracket in, use a dremel with cutoff wheel to cut off the extra screw threads. Grind the screw down to the nut (don't muck up the nylon though!) and it should clear the body when you close the door.
As far as the proper arm to attach to the actuator... it's the smallest one in the kit, with two 90* bends. (if you buy the new power lock kit, you'll see two little baggies with a bunch of arms you can put in the actuator). Once you put the arm in the top of the actuator, line up the holes and hammer the split pin into place so that the armature won't fall out.
Install the actuators by sliding the armature into the bushing on the lock mechanism (little orange/yellow disk) and then extending the arm on the actuator. Now you have to reach in and get the two nubby arms sticking out of the actuator into the pivots on the mounting bracket. A wide-jawed pair of pliers work decently for this.
Both of my new power door locks functioned fine when 12v was applied to them, but after I installed them, something wasn't kosher. It would lock OK, but would NOT unlock.
My first impulse was to check the wiring harness that connects to the actuator. I was getting a clean voltage and about 3 amps for "lock" but an erratic voltage reading and only about 1.75 for "unlock"
After some investigative work, it turned out that the switch on the door's arm rest was the culprit. Unscrew the bezel from the door panel, pull out the wiring harness, and flip it over. Now unscrew the bezel from the switch panel(two screws on the back). Then I popped the switch out of it's holder (push up from the underside of the switch panel on the pink "L" shaped piece), cleaned all of the contacts on both the switch and the receptacle, and plugged it back in. On the receptacle, you can use a tiny screwdriver to bend the contacts back together, so that they grip the pins on the switch better. Voila! Operational power locks!
Some electrical notes:
-If you have either one of the power lock switches disconnected, the entire system will NOT work. Each switch has bypasses built in that allow the opposite switch to work. If one is disconnected, then you have an open circuit.
-To test the wiring harness, take some wire (make sure it's as thick as the wiring that's already on the harness, or thicker) and shunt one of the outside pink wires to the black wire immediately above or below it, and then shunt the center black wire to the pink wire you already shunted. If you get it wrong, you will see sparks! If you get it right, the actuator should work. It's also a good idea to check this with a volt-ohm meter.
-Nominal switch output (as measured between a pink/black wire on the same side) 12.40 volts at 3 amps
-Replacement power lock switches are expensive, so don't lose it!
Hopefully this info helps someone out with their power locks, since they are essential to installing an aftermarket alarm.
-dumba$$ lessons learned: extremely thin gauge wire at 12v/3A will burn flesh instantly. The sheetmetal edges on doorpanels are SHARP.