Power window wiring

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adam f

Not-quite-so-new-guy
Apr 13, 2010
6
0
Help...working on a 1981 GMC Cabellero. Passenger side power window inop (drivers side has a mis-match door with manual window)

Took my meter, hooked ground to body, and probed the connector to the motor. I had 12v using the switch going both up and down. So I figured it had to be the motor.

Replaced motor and it still doesn't work.

Should have realized I was using a different ground than what was being supplied to the motor.

I can use a jumper and put a good body ground to the switch, hit it, and the motor works.

So, I have a bad ground going to the motor.

My question is, where is this ground coming from? I found wiring diagrams for this car, but nothing showed the power window system.

Could it be a bad switch? Keep in mind using a separate ground, the 12+ switches on and off just fine, but using the ground at the plug at the motor, it does not.

Anyone have a wiring diagram for this car that shows the power windows? Or has someone come across the same problem? Is there some sort of relay or something under the dash that switch runs through?


2nd unrelated question......are the wiper arms on this car interchangeable from left to right? I need a replacement on the passenger side, but I can only find a part number for a driver's side.
 

454muscle

Royal Smart Person
Jan 31, 2010
1,251
0
Ontario, Canada eh!
I can only guess (so this isn't definite, but the Elco owners would know better), but I think they are the same for all G-bodies, meaning left and right wiper arms will not be interchangeable.

Dunno if anyone will be able to help you with the wiring problem you described. You tested the motor and it worked fine. So test the switch on a light bulb. A circuit tester, by the way, is REALLY handy, and cheap enough, makes life so much easier. Use it to deduce, step by step, where you're losing ground (or power) connection. ;)
 

RegalBegal

G-Body Guru
Jul 10, 2009
702
93
Claremont, NH
The ground comes from the window switch. There are 2 wires from the switch to the motor. All the switch does is change polarity to make the glass either go up or down. Check the ground at the switch or the switch itself.

PowerWindows.jpg


Hope this helps
 

adam f

Not-quite-so-new-guy
Thread starter
Apr 13, 2010
6
0
Thanks for the diagram.

On the switch, there are 5 wires on it. Tan, brown, 2 blue wires, and red.

I dont see the brown wire in this diagram. Could this be the ground?

Also, the diagram does not show which wire is ground.

And the master control switch is not hooked up. I wonder if this affects anything?
 

RegalBegal

G-Body Guru
Jul 10, 2009
702
93
Claremont, NH
Forgot to mention, this diagram is for a malibu so it might be slightly different. Also, if you look at the bottom, you'll see the ground is at the motor.
 

Doober

Royal Smart Person
Apr 8, 2007
1,253
38
Swartz Creek, MI/Tucson, AZ
Most GM windows are similar.

RegalBegal said:
Forgot to mention, this diagram is for a malibu so it might be slightly different. Also, if you look at the bottom, you'll see the ground is at the motor.
Yes, the motor grounds though its body, making its way through the door shell & body back to the battery.
 

adam f

Not-quite-so-new-guy
Thread starter
Apr 13, 2010
6
0
Are we 100 percent sure the motor grounds to the body? Must be different on my 81 Cabellero.

Thats what I originally thought. I tested 3 different motors by grounding the body, and putting 12+ to each terminal, and nothing, on ALL 3 MOTORS. 2 new and 1 old.

So, I tried putting negative on 1 terminal and positive on the other terminal, and it worked. Switched polarity and it reversed.

So somehow the switch sends pos and neg to the motor, and reverses polarity.
 

adam f

Not-quite-so-new-guy
Thread starter
Apr 13, 2010
6
0
Ok, I downloaded a 85 monte wiring diagram and found one that is like mine. The ground comes from the master switch in the left door.

Problem is, previous owner replaced the drivers door with a manual window, so the switch is not there anymore. Looks like it needs that ground, or possibly the whole switch, to operate.

Can anyone think of a way to wire it without the switch?

This is the diagram that looks like mine

http://www.badss.net/other/monte_85_wiring.pdf
 

adam f

Not-quite-so-new-guy
Thread starter
Apr 13, 2010
6
0
I found the wiring, and grounded the wire. Still not working. I guess I need the master switch for it to work.
 

84GP455

G-Body Guru
Jun 19, 2007
782
28
Methuen Ma.
Yes you need the master switch in order for the motors to both work. It's a loop circuit and it needs both switches and motors to work properly.
 
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