Power door locks don't work, where to start?

[Slow&Low]

I just picked up a new to me 91 ESCB a few days ago, and the power door locks won't work from the switches on either door. I've tried searching but everything I've found seems to pertain to newer trucks. From what I have gathered in searching, is that there is no relay and that they're wired direct? Seems strange to me that there'd be no relay for them.. I've tried checking the interior fuses underneath and to the left of the steering column, but that's as far as I've gotten. Can anyone tell me what else to look for? Anyone know which wires coming out of either door I could hit with a test light to see if the switches are working without taking off the door panel? TIA.

 

[Swims350]

Well if the fuses are good, check in the boot, the rubber thing in between the door and cab when the door is open, the plugins are in there, see if they are all plugged in.

check the switches, on my 88 the window switches would work the locks and the locks would work the windows, so if your power windows work, try the door switch in the ds window in the ds door and see if the lock switch moves the window or not, if it does then the switch works, if it don't the switch is bad. Try both door lock switches in the ds door ds window part, and see if they both work. If one is bad they are like the power windows neither will work I'm pretty sure, like christmas lights if ones blown they all don't work.

Now if you know for sure you got 2 power window switches that work, put those in the door lock spots and try them. If that don't work and the fuses are good check them things for power right where the switch plugs in, if you get power then I'd think the actuator is bad unless the wiring is tore up inside the door.

There is a relay in the older trucks but I aint sure if it's the doors or windows. I know there's one hanging down under my dash in my 88.

 

[Slow&Low]

Well if the fuses are good, check in the boot, the rubber thing in between the door and cab when the door is open, the plugins are in there, see if they are all plugged in.

check the switches, on my 88 the window switches would work the locks and the locks would work the windows, so if your power windows work, try the door switch in the ds window in the ds door and see if the lock switch moves the window or not, if it does then the switch works, if it don't the switch is bad. Try both door lock switches in the ds door ds window part, and see if they both work. If one is bad they are like the power windows neither will work I'm pretty sure, like christmas lights if ones blown they all don't work.

Now if you know for sure you got 2 power window switches that work, put those in the door lock spots and try them. If that don't work and the fuses are good check them things for power right where the switch plugs in, if you get power then I'd think the actuator is bad unless the wiring is tore up inside the door.

There is a relay in the older trucks but I aint sure if it's the doors or windows. I know there's one hanging down under my dash in my 88.

Awesome, thanks! Someone on GMFullsize linked me to the wiring diagram for my locks (http://www.someotherplace.com/guides/locks_2door.jpg)

I'm going to try and take a multimeter to the wires coming out of the doors and see if I get power, I'll swap the switches if I need too, thanks!

 

[Slow&Low]

Blah, still not working..

So far today I've determined that I'm getting power to both switches (so it's not a fuse), Both actuators work correctly when power is applied to them, and as far as I can tell both switches are good (as far as I can tell)

I was having a hard time checking the grounds of the switches with my multimeter due to not enough hands, but with my test light grounded, I know they're putting out positive on their 2 separate wires like they're supposed to. There's also a 12v+ wire at the switches at all times (like theres supposed to be). I've checked both switches on both doors at the back of the switch, as well as at the connection in the kick panel. I've also jumped the connections at the kick panels on the tan and grey wires with an external 12v battery on both doors separately, and the actuators function flawlessly in each direction when I apply the power directly to them.

I also tried the method above with swapping the window switch and lock switch, except the harnesses plugs were different, I pulled the wires from it and placed them in the same corresponding positions on a known good working window switch, and the locks still wouldn't function. I didn't disassemble the window plug to try and see if the windows would work with the lock switch however.

The only thing I have to be missing is ground, correct?

If I have no resistance from the 2 grounds at the back of the switch, and the chassis directly, where is the ground wire in the harness in the schematic above, connected to the chassis at? The diagram says in the convenience center under the left side of the IP, I assume that's the box looking deal beside the brake pedal with all of the colored plugs in it? I didn't see any obvious missing connections from that box, anyone have a picture of where this system is supposed to ground at?

I'm thinking the ground is the missing link in this circuit, probably wherever it is supposed to be grounded under the dash..

Thanks in advance to anyone who has any more insight or help!

 

[Swims350]

hmm so your window switches are different from the door lock ones as far as pins on the back?

 

[Slow&Low]

The pins are the same configuration, but the plastic sleeve the wiring is in has different slots in it so they can't be plugged into the wrong switches.

 

[Swims350]

slots? did you have them removed the plugin from the door panel piece? Mine had the same number of holes in them as the pins and same configuration I don't remember any slots or anything mine plugged right into each other no problems.

 

[Slow&Low]

Yeah, there's orientation slots in the plugs on mine, so you can't plug them into the wrong switches.

Here's a pic to show what I'm talking about.. The grey plug is for the Power Locks, the white one is my drivers window switch.

http://i702.photobucket.com/albums/ww28/ckenda6/SU1BRzA0MzAuanBn.jpg

 

[Swims350]

well SOB, I see what you mean now, sorry about that man I hoped they'd work, I know mine does, but mins an 88 and doesn't have slots in it. Sounds like it you tested them anyways without them being in the plug that it didn't work anyways. Seems weird they work if you apply power, yet they get power to the plugin? and they get power to the actuator? Definately sounds weird, but a ground or bad ground, lack of, could cause issues. I aint really sure on the diagrams and such for one, so don't know if I'd be much help or not.

Sorry about the info on the switches though man, I didn't know they had slots. My 88 is my first obs/99-09 style truck to own or work on. I mostly worked on square body trucks like 73-87's.

 

[kon68]

Hello there I'm a newbie and I know this is a old thread but I'm having some of the same problems and I have a 97 Yukon and all my windows work and all my locks work but one passenger side front and if that door lock don't work my rear power hatch don't work either. I changed everything but the the passenger side switch and still the same thing and I'm getting power but there is a module under the dash slightly left of the gas peddle I changed that also and still the same thing I have on thing left to do the switch and hoping for I here that these trucks do that