Power door locks dont work

[LordVngr]

Power door locks dont work - Duplicate - Please delete

I have power door locks on my 89 Stx But they have Never worked since day one and I'd like to get them fixed. When you press the switch nothing happens at all.

I've checked what fuses I know of and those are ok. Havent done any troubleshooting with a test light yet though. I'm thinking it's the actuators inside the door. Seems I heard that rain water leaking past the window seal has a tendency to burn them out. Any truth to that.

I would just Buy them / try them But those puppies are about 60 bucks apiece minimum new. Cant Return Electrics you know. I also dont really want to deal with a salvage yard either, Probably play hell trying to get 2 good ones.

So my question is besides the fuses is there anything else Other the the aucuators that might be causing the problem and is there a way to them first so I know there Bad Before I buy them. Thanks...


LV

 

[RobbieD]

Pull off the driver door panel, unplug the actuator and put a test light or VOM across the 2 terminals in the plug on the harness (not actuator). Work either switch- if the light lights or meter shows power present, that would indicate that the actuator is bad. If this test shows no power, then the problem is up-circuit, being in order the passenger switch, the driver switch, or the feed wires going into the driver door. Generally, you'll find the problem in either switch, or as a break in one of the wires, as opposed to both actuators being bad. It's not hard at all to diagnose, as long as you understand how a reversal-rest-at-ground circuit works. Good luck!

 

[LordVngr]

Thanks for the info. To tell you the truth, I'm not real sure what your talking about when you say " reversal-rest-at-ground circuit works ". I will say that I tested the switch's last night with a simple test light and this is what I found out.

The door lock switch itself has no power to it weather the key is on or not. when I push the power door lock button up or down one wire on each side of the switch then becomes hot and lights up the test light But the wire next to the hot one never becomes hot and if I jump those wires together and then press the switch nothing happens. I also noticed on the drivers side switches someone has cut and spliced into the power door lock wires what looks like speaker wire for some reason. Not sure why and I havent traced those wires out yet. As for the actuator switch iteself I havent tested it with a test light yet But I will. Does that make any sense to you and give you any more ideas. Thanks...


LV

 

[RobbieD]

First of all, there's a wiring diagram in the tech section, which I'll try to link here for you:
http://www.therangerstation.com/tech_library/EDiagrams/files/Diagram_Powerdoorlocks_1989on.JPG

The important thing to understand about a reversal wiring circuit, is that the wires throughout the circuit, except for power feeds, normally "rest" at ground. When either switch is operated, one set of wires (think "lock" or "unlock") changes from ground to power; in other words "reverses" polarity.
An actuator isn't grounded to the body; it's grounded by the wire that doesn't change polarity. DO NOT connect two wires together and operate the switch; that will be a direct short and damage the switch.

Back to troubleshooting your truck. Notice that the whole doorlock circuit starts at the driver switch, then goes to the passenger switch, then from there goes to the two actuators. So it's best to start at the beginning, then work your way down.

At the driver switch, check for power on Black/White wire, AND check for ground on both Black wires. If either is not there, you gotta fix this first.
If both power are ground are there, put your light or meter ACROSS the Pink/ Lt Green and Pink/Yellow wires, then work the switch. No light/meter reaction means a bum switch. If you do have power and ground here, move to the passenger door switch.

Check the passenger door switch as follows:
#1 Check across the Pink/Lt Green and Pink/Yellow for power and ground, operating the DRIVER switch. If none, correct the open circuit between the switches. If power and ground are found, test:
#2 Check across the passenger switch Pink/Orange and Pink/Black for power and ground, operating the DRIVER switch. If none, passenger switch is bad "at rest" (open circuit). If power and ground is found, test:
#3 Check across the passenger switch Pink/Orange and Pink/Black for power and ground, operating the PASSENGER switch. If none, passenger switch is bad "in operate position".

If your tests are good to this point, then repeat checking for power and ground at both actuator plugs.

Basically, it's really just a matter of studying the circuit diagram and understanding how it works. The most common problems with these doorlock circuits are:
- Lack of power OR ground at the switch, especially the driver door "master" switch.
- Bad switches, having bad contacts from corrosion or past short circuits (which creates an open circuit or non-switch condition).
- A broken wire, which creates an open circuit.

Be aware that the doors' wiring harnesses go out of the doors and all the way around the front of the engine compartment; that throws a lot of people for a loop when they're trying to trace them. I hope this somewhat long-winded explanation makes sense, and is helpful in your troubleshooting.

Good luck!

 

[LordVngr]

I hope this somewhat long-winded explanation makes sense, and is helpful in your troubleshooting.

Good luck!

Robbie

You have been Most Helpfull and I will print out your post and diagram so next time I go to work on it I have a point of reference to start with. I'm pretty sure it has something to do with someone many years ago cutting the lock wires and splicing the other wires in for something . They probably messed up this Ground your talking about. I Still havent traced them yet But I will as soon as I can.


I'm pretty good when it comes to turning wrenches But my electric experience is Very Limited. I can use a test light to see if something has power to it and I know how to check for resitance on a ohm meter, Etc , But most of what you said is over my head.

For instance how do I check something for Ground?

Thanks...


LV

 

[RobbieD]

Regarding "For instance how do I check something for Ground?", the down and dirty way is to attach a test light clip to a good 12 volt (Positive) source, and Ground (Negative) will be indicated if the light lights up when the probe end touches the target. Good bright light, good ground; dim light, weak ground; no light, no ground.

Of course there's other ways, but this one is simple and it works.

I think as you actually work on the truck's wiring, and study the electrical diagram, things will become easier to understand as you go along. It ain't hard, and you'll be fine.