Replacing Window Motors in 1988 GMC Suburban

[JasonTL]

So, the next thing on the list for my 88 GMC Suburban is getting the 4 power windows working. I replaced the fuses because that was a cheap possible way to fix their operation.
Unfortunately that wasn't the problem.

They are all stuck in the up position and don't move when I use the window up/down buttons on any of the doors. The front passenger window is stuck mostly up(it's down about an inch). Currently it is taped to prevent rain from getting in.

I'm thinking I need to replace the window motors. I've done some research and it seems fairly easy. I'm wondering though if there is anything special I should know that I may not have learned yet? I know I'll need to drill out the rivets. One thing that has me concerned is I sometimes read about a spring that can do some damage if not held/bolted correctly. Not everything I read mentions this though so I am concerned whether this will be a problem and if so how do I prevent/minimize the issue?
Also, do the windows need to be up or down when I replace the motor? I've read mixed things about this as well.

Another thing is my tailgate window will go up and down if I use the key in the tailgate but the button upfront won't operate it. I assume this means the button is bad? Is that an easy replacement?

Thanks.

 

[AandPDan]

I'm not familiar with your Suburban but having 4 motors all fail seems a bit unlikely.

It's a DC motor. Rig some wires to a battery and apply power to the motor, in or out of the truck. One way should make it go up, the other down.

 

[Trav]

I wonder if this has cables like the 2002? I did one that had 3 out at the same time, the cables had frayed and jammed the works.
The only fix it to replace the motor assy if thats the case.

This vintage may have the old scissors unit, i'm not sure.

 

[Nick R]

Maybe the wiring where it passes through the door to the body is frayed? That would do it as I agree it seems unlikely they would all fail. Check that first, the wiring where it passes through the door into the truck. Over time I bet the friction of the door opening and close would crack and strip the brittle old insulation.

 

[JasonTL]

The truck has sat dormant for 2 years and I think the two middle windows didn't work then.

I have not taken the door panels off yet to see. Can I take the panels off and check and still drive safely without putting them back on? Or are they going to be easy enough to where I can check all four then throw them back on to drive it?

If the cables are the problem, can I replace those with relative ease?

 

[c502cid]

Before you replace the motors, the 73-87 (to 91 on Subs and R/V series) door switches are all prone to wear out. Not saying you wont have to replace the window motors, but the contacts on the GM switches get dirty and worn down to the point they aren't doing anything.

Ask me how I know this...lol

If you have to do window motors, they aren't that hard, it helps if your hands are small, not a whole lot of room to work. Plug in the motor before you install it just to be sure it works. Scissor type of assembly, check track bushings while you are at it too. A little grease in the slide channels will go a long way for longevity.

 

[SteveSRT8]

The whole point here should be correct diagnosis first.

Don't just start changing parts!

 

[JasonTL]

Alright, really glad I posted. Was planning on buying a motor tomorrow but now I'll wait and open up one of the doors to check what y'all have mentioned.

@c502cid, 'How do you know this?'

How do I test the switches?

Any particular grease for the channels?

Is there any specific door that would be best to diagnose and fix first, or does it matter much?

 

[SteveSRT8]

The door panels pop right off, but the switch can easily be checked with a continuity test light. Use a spray grease on the channels, or silicone as it is clear and won't be as messy (or last as long).

You need to be sure there is power. I am curious about the fuse you replaced as most of that vintage would have had a circuit breaker on the PW/PDL stuff.

 

[JasonTL]

I noticed two large metal encased fuses in the fuse box. I did not replace those.

Here's a picture of my fuse box. Sorry if the image is too big. This is my first time posting a picture on these forums.

I assume that one metal encased fuse labeled '30A 12V' with the '30A PWR WDO' is the power window fuse. Is that the circuit breaker? I looked online at Advance Auto parts and couldn't find that part. I think I tried putting a normal 30A fuse in there and it didn't do anything. I'm guessing that was probably pretty dumb now...The fuse didn't break though.

Would this fuse being blown affect my rear tailgate window? That window works when I use my window key in it but not by the front console button.

 

[SteveSRT8]

If it works then it's not that fuse/breaker.

But the rear window may be an optional piece and thus have its own circuit.

Those metal things are circuit breakers, they usually do not fail, but you are getting up there in age.

 

[JasonTL]

We have an identical Chevy that has barn doors. I imagine there could be GMCs with barn doors so I suppose the tailgate window may be optional.

I think I found the right circuit breaker for it now that I know it's a circuit breaker. This look about right?

I'm going to be buying some wipers today anyway. Think I should grab one of those circuit breakers since it's only $3.50? Or would it be better to test something else first?

 

[exranger06]

If you put a fuse in place of the breaker and the windows still didn't work, and the fuse didn't blow, then there's no problem there. Replacing the breaker won't fix your problem.

 

[Doog]

My guess...the main switch on the drivers door. My daughters Honda just did the same thing and the plug on the back of the master switch had fallen off.

 

[JasonTL]

Alright, so I chose not to buy the new breaker because the one I found in the store looked smaller and I didn't have that car with me at the time. I'm going to drive it in next week and bring the breaker in and see if I can find the right one.

I also haven't opened the door panel yet. I want to either this sunday or monday. Looks like there's quite a few things for me to look for in there. That would be really amazing if the switch had just come out.

Did I mention previously that no window buttons work? The buttons on the respective doors don't operate them and neither do the driver's door. Does this help locate the problem any?

 

[JasonTL]

So....I took the door panel off today. It took a bit of trying since it was my first time but after getting the pesky clip off I was able to get the panel off. I found the motor, regulator, switches and wires and the motor wire.

I tested continuity on the switch, seemed fine.
I checked the voltage on the wire that plugged into the motor and it was only reading 0.01-0.04 volts when I put the switch on. Shouldn't this be reading higher?
I did not check the window motor itself yet because I'm not exactly sure how to do it safely. Can I just hook some wires to the terminals and then connect one end to the battery and touch the other wire to the other battery terminal?

Currently the window is taped to the door and I put a prop under it to keep it from falling. Hoping we can figure out what is wrong with it soon so I can put the door back together. I don't like the feeling of leaving that glass there but I didn't want to put the regulator back in(was a little annoying to get out).

Does any of what I did today help locate the problem better? Anything else I should try?

 

[exranger06]

Originally Posted By: JasonTL

I did not check the window motor itself yet because I'm not exactly sure how to do it safely. Can I just hook some wires to the terminals and then connect one end to the battery and touch the other wire to the other battery terminal?

Yes, it's perfectly safe. Connect them one way and the window will go down. Reverse the terminals and the window will go up.

 

[JasonTL]

Well, this is most perplexing...

What I tried today...
Tested continuity on the circuit breaker, seemed to be fine.
Tested between circuit breaker terminals in the fuse box and the window motor connector, seems fine.
Tested switch again, still seems fine.
Tested connector that connects to the back of the switch, no power. Tried with the accessories on and off and still no power.
Tested the circuit breaker terminals in the fuse box and there doesn't appear to be any power getting to them.
Finally I checked the motor by placing two pieces of 12 ga romex into the back of the motor power connector and then connected it to the motor and then touched the two ends of romex to the battery terminals. Motor didn't budge nor make sound.

So....
My motor might me bad.
But shouldn't I be able to find power at the circuit breaker terminals in the fuse box? It seems like I might have a problem in my fuse box or one of the wires leading to it. If this is the case, any ideas on where to start looking for the responsible wire?

Tomorrow I plan on monkeying around under the dash and steering wheel to look at all the wires and see if I can find anything damaged or not connected.

Anyone ever had a window problem this deep? Or maybe I tested something wrong and that's misleading me?