power window Rear Driver door window isn't working. Won't come down.

Jim Gosselin · March 4, 2020

My rear drivers side window would not come down. This just started the other day. It would not work with the front or rear switch. no humming from the motor. Fuse is OK for the left side windows. I swapped out the switch from the passenger side and still didnt work. However the driver's switch worked fine on the other side. I then removed the regulator assembly by having to cut the cable since the window was up. I removed the motor and bench tested it and it ran with 12V put to it. This leaves just the main front door switch assembly. My question is would a bad front switch cause the back switch not to work?? Also when I press the switch , I get a brief buzzing sound from the switch. Also with the motor connected, it still isnt turning so it wasn't a jammed cable on the regulator. I am getting to the end of what I can troubleshoot, and I hope it doesn't turn out to be a bad wire in the door harness. Any suggestions would be greatly appreciated.

ramjet1121 · March 8, 2020

I'm having a related problem. My left rear regulator was bad (cable/pulley problems, and I replaced it with a new one that included a new motor. All was well for 5 months, now the window will not operate at all from either the rear or front switches. I thought the motor was defective, although pretty new. I disconnected the motor and measured motor resistance, which seemed to be ok, I think (about .5 ohm, similar to old motor which was working). Tried to measure voltage to motor from switch, but could get no reading. With all the wires going to the rear switch and no schematic, I'm not sure what to expect. I've been searching for a wiring diagram with no luck. Can anyone help?

davester · March 8, 2020

gmupfitter.com should have the wiring diagram. Or you could get subscription to the full-service manual at a site like alldatadiy.com for not much money (this will have both the wiring diagram and how to diagnose what's going wrong)...

Edited March 8, 2020 by davester

Jim Gosselin · March 9, 2020

New regulator and motor. No luck. New front master switch and still no luck. I give up.

Lsgun1 · March 9, 2020

First thing you should have done is check for power/ground at the motor. You probably have a broken wire in the door harness that runs into the cab.

Jim Gosselin · March 12, 2020

Well I found my problem. It was a broken red wire which is power to the rear door switch. I found the wire in the rear door wiring harness. There were 2 other wires in question with either nicks in the insulation or possible break. I cut and spliced these as well just in case. The red wire was corroded too and broken clean in half with plenty of slack to do the repair. I also had an issue with the connector to the rear door switch. I ended up removing all the pins and "refreshing" them by pressing gently to tighten up where thay make contact to the actual switch connection. As of now all is well.