So I've got this 1992 Ranger extended cab with power door locks and neither side is working. It has power windows too and they work fine. I checked the 30amp fuse under the hood for the power door locks and it's good and checked it with a test light and it's good. What's most likely the cause that both sides don't work? Is there a way to troubleshoot with a test light to trace down the problem as a bad switch or actuator?

 

could be a bad relay, I dont have a schematic handy so cant tell. If you go to a dealer parts they can run a schematic for you as to where the relays are. I think they are down in the left kick panel not sure.

 

My 94 Taurus electric door locks got wimpy. Unsnapped the door panel switches & cleaned/burnished their contacts with a New/Clean/Stiff dollar bill & that Woke them up, still working ok with Gusto, 7 years later. Gotta go back in & re-do the window switches again though, as a couple have gotten slow/lazy going up & down.

A member over on TCCA had the same problem with his Taurus locks & windows, didn't have a new dollar bill, so he used the only thing he had, a $100!!!!! Yup you read right, cut up a brand new Ben Franklin, But he saved the pieces, taped them back together so the serial numbers were readable & the bank replaced it. He said he also used some cleaner on the strips as he pulled them through the contacts & yes he got Joy!!!! lol If you decide to use a contact cleaner, consider using one that's plastic safe & won't leave any residue after it dries, like CRC MAF, or CRC QD spray cleaner. I'd not spray the contacts directly, as there are all kinds of plastic around the contacts, that might not like the cleaning solvents, as many solvents can cause stress cracks in some plastics, just dampen the item your using to tidy up the contacts. No need to have it dripping wet, damp will do. Clean All of the contacts & let us know how it goes.

EDIT: If you don't want to use money, try a 2000, 1000, 600 grit we sand paper to polish the contacts I'd not use anything below/more course than 600 grit, so as not to remove any contact plating. We just want to lightly burnish/clean the contact surface, to lower/improve its electrical resistance.

 

Ok I did the contact cleaning. That didn't help. I finely smoothed the pins with 2000 grit sandpaper. I also used the CRC MAF to clean them after. Well I also got a diagram of the power door lock system. I'm working on the master switch now on the driver's side. It has a blue/light green wire and black at the top of the switch and a blue/yellow at the bottom. One is for lock and unlock. I used my test light and tested for power each time I press unlock or lock on the blue wires. Each showed power while pressing unlock or lock. I forgot how to check if it has a good ground but maybe that's what I just did. I'm no electrical tech. I fooled with the wires while pressing the button to see if anything might be frayed but got nothing. Same thing on the passenger door too. I guess this means bad actuators? Sorry don't know why it posted twice, first response said error encountered, try again.

 

So I cleaned the contacts using the CRC MAF cleaner and the 2000 grit sandpaper and nothing changed. I tested for power to the switch with my test light. There's two wires for the unlock and two for the lock. When I press unlock the blue/light green shows power and lock the blue/yellow wire shows power. Same on the passenger side too. What does this mean? Bad actuators? I didn't want to take off my door panels yet because they are in such good shape.

 

When you press the lock/unlock switch, can you hear, or see the lock motor move the door lock pin that sticks up????

 

I don't hear any movement at all. I didn't take the whole door panel off until I know it's not the switch because I don't want to take them off unless I have to because they never to seem to fit quite as good as before the first time they came off. If it's the actuator would both be bad or just the driver's? How often do both sides go out?

 

What I was trying to determine was if the locks were trying to work at all. If not, then it may be a power feed problem to them. If they're trying to work, the lock motor may be rusted up internally, or its current limiting thermistor may be bad. If its the latter, we can short out/jumper the thermistor, to give full power to the lock motor & it'll often wake up & work. There are photos & videos on the net on how to rework the lock motors.

 

When I installed power stuff to my 94, I had switches that would not work and ended up replacing them. Had power, had good relays etc, just nothing at the switch. You will need to check the switches for continuity and that will require pulling the panels off. With a volt ohm meter test the switches in ohm position to see if they have a completed circuit. Can also do this as you indicated with the power light but dont know how you are getting power on both sides at same time as your wrote? There are circuit boards also that may need to be checked for a broken traces/cold solder joint. Again this can be done with the ohm meter.

But make sure you have 12 at the switch 1st.

 

No I had power with my test light when I pressed unlock. Then I switched to the lock terminal wire and had power when I pressed lock. So is the next step to take the door panel off and unplug the door lock actuator plug and hit unlock and see if it has power? Then do the same for lock? If it does then the motor is bad?

 

A test light is ok for rough checks, but you need to be more accurate in your testing, so break out your multi-meter & perform some under load voltage drop tests on your door lock circuit. From page 2 in our "Battery Tutorial" thread, a link on how to do voltage drop testing. Voltage Drop Testing

If you can't hear, or see the door locks trying to work, you need to remove the door panel & check the lock motors mechanical linkage & wiring condition. As I mentioned earlier, moisture can get into the lock motor & electrically & mechanically muck things up & the current limiting thermistor can so limit current draw, that the lock motor gets too wimpy to move things, so cleaning things up inside & shorting the lock motor current limiting thermistor with a piece of jumper wire, will often wake the lock motor up. If you find excessive voltage drop across the lock switch, unsnap it & burnish the contacts as described in my above post.
If you don't have small kids that like to hold the lock switch in position, you'll be ok to short the thermistor out.

There is a multi-page thread in the Explorer forum here https://www.ford-trucks.com/forums/4...cks-fixed.html with photos on page-2 on how to open the lock motor up to do the rework, if you find that the lock motors need it & you don't want to buy new ones.

Harbor Freight has two door panel removal tool kits that'll be helpful in removing the panel push pins, so they can be reused. One is blue, the other is yellow, I have the less expensive yellow one & its ok for occasional use, the blue one is more heavy duty, but costs more, your choice. If you damage/stretch, or break one of the push pins, I've seen Ford type replacements in my local O'Rreilly auto parts store.

More thoughts for consideration, let us know how your trouble shoot goes.