1990 Suburban Rear Passenger Window Switch

[gmbellew]

The rear passenger window switch stopped rolling the window up. The window operates normally from the driver switch. The window operates down from the rear passenger switch. I looked at the wiring diagrams and followed the troubleshooting in the wiring manual (shown below for reference). I get to step 4, and there is not 12v between BRN and DK BLU when the switch is pressed in the UP direction. They do show 12V when the switch is pressed in the down direction (and the window rolls down). So this led me to believe the switch was bad. I had to order 1 switch, so with shipping being more than a switch, I just ordered 3 switches. Replaced the switch, and the window still doesn't roll up from the rear passenger window switch. I tried 2 more switches, and UP does not work but DOWN is fine. I get 12v between ground-BRN and ground-DK BLU when the switch is pressed up. But i do not get 12v when between BRN and DK BLU when the switch is pressed up as described in step 4.

is it possible that something in the window switch connector is bad/loose, or does this sound like something else? I'd like to get some ideas before I try to rip deeper into the door or potentially break the connector trying to take it apart...

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[Snoots]

It sounds like a break in the wire from the switch to the BUSS for the motor.
You'll have to manually trace the wire from the 'bad' switch to the harness.

 

[gmbellew]

It sounds like a break in the wire from the switch to the BUSS for the motor. You'll have to manually trace the wire from the 'bad' switch to the harness.

My understanding is the motors are reverse polarity. For the rear passenger window to go DOWN from the rear door switch, BRN is hot and DK BLU is ground. This works. For the rear passenger window to go for UP from the rear window switch, DK BLU is hot and BRN is ground. This does not work. I figured that since the window rolls down, both wires are good from the switch to the motor. Because if one wire was bad, the window wouldn't have ground to go down. I think the power and ground from the driver door master switch runs through the rear window door switch and into the DK BLU and BRN wires that go to the motor. So since the driver door master switch works ok, it seems that there isn't an issue with what is running from the window switch connector to the motor, and the grounds and wires are good all the way back to the driver door or the master switch would not work. I have been staring at the schematic and troubleshooting procedure and can't figure it out. All I can figure is I have really bad luck with switches or the connector has an issue?

 

[gmbellew]

i opened up the window connector, and it looks like the day it was built. i will try to source a different brand of switch to see if i just happen to have a bad batch. other than that, i am out of ideas...other thoughts?

 

[gmbellew]

I am having trouble sourcing a different brand of switch than CUB. but I had a helper today to check some scenarios from the driver switch. when the driver master switch is used to power up the right rear window, I meter 12v between DK BLU and BRN like it is supposed to be and the window goes up. I still get 12V on DK BLU when I push up on the right rear door window switch, but the window doesn't go up and I do not get 12v between DK BLU and BRN indicating BRN isn't grounding when the switch is used to power the window up. all I can figure is that these CUB switches are bad or there is some weird scenario that I am getting ground from the BRN wire when the master switch is used but not when the rear door switch is used to power the window up. but looking at the schematics, I don't see how that is possible.

 

[gmbellew]

Fixed the issue finally.

A couple different brand switches didn't fix the issue. So I figured the only thing could be the driver master switch isn't grounded at rest like it should be, but would ground properly when the master switch was used. I had an old switch in the garage to test, so I pulled the driver switch. I am not sure if the switch was bad, or the tube of dielectric grease somebody had smeared in there way too thick was the issue. But the rear switch works properly after the driver connector was cleaned up and the switch was swapped. I guess the GM trouble shooting guides can't cover every crazy random scenario.

Now I have plenty of spare switches and connectors for the next 30 years!

 

[NCBurb]

I just wanted to think you for posting up the solution! So many times I find threads asking the question I need, but no answers! Glad you got it figured out, I still have a few bugs to work out, but every clue helps...