None of the power windows work in my 1972 Cutlass Supreme convertible - 455 cu. in. There is power coming out from the fuse block at the circuit breaker but nothing at the the driver's door master switch block. The rubber covering on the wires from the driver's door to the body is intact with no tears in it or sign of broken wires. (I am the original owner and there is only 140,000 miles on the car.). I'm thinking the relay may be the problem, but I can't find it behind the dash or by the steering column. Is it behind the kick panel on the driver's side (I hope not)???? or on the firewall ???. Any help would be appreciated. Thanks.

 

Thanks for posting and welcome.Electrical issues can be irritating and the solution requires patience. You didn't indicate if you have documentation in the form of manuals for your car. The Fisher Manual contains helpful information and the Car Service Manual contains wiring circuits and other detail information. I'd strongly recommend that you obtain such documentation for your particular automobile. A simple tool like a test light is also very helpful in these circumstances.

Good luck ~

 

The power relay is behind the kick panel in a tough to get at spot. If the relay clicks when the key is turned on, it will be easier to find. Have fun.

 

The usual culprits are a dead relay behind the driver’s side kick panel and/or a broken wire inside the rubber door boot between the door and body of the car.

If the main power window inbound supply line to the switch has broken no windows will go up or down.

The reason they break is that they bend every time you open and close the driver’s door.

Diagnose with an electrical diagram to find the color of the inbound supply wire and a test light.

Chris

 

If it ends up being a broken wire in the boot between the door and a-pillar DO NOT splice it back together where it is broken. You need to either cut out that section of wire at the kick panel area and in the door and pull it out and run a new wire and make your splices at the kick panel and in the door were there will be no stress on the spice when the door opens and closes. Or you can cut the wire and leave it in there and just overlay a wire on top of the harness and splice it in the same places mentioned above. Your choice.

 

This was a poor design by GM. Wires bending horizontally will eventually break.

 

Wires breaking inside the door jamb boot isnt a GM design problem, every car market suffers from that concern. You can only flex a wire so many times before it eventually breaks.

 

The later design has the wires dropping a few inches from jamb to door. This causes the wires to twist instead of bending making them last longer. Northern (Western) ,Electric knew this when designing their compact telephone systems for the Carribean Islands.

 

//Enable Sarcasm mode:
The wires would survive if they were designed to bend vertically.
//End sarcasm mode.

edit:
No offense intended, it’s Friday night and I’m feeling rowdy.

 

Thanks you all for your comments. Taking off the kick panel is my plan. I will replace the relay anyway at that point (after all that work) since it is 51 years old! I'll have the new relay in a week or so so it will be a few weeks before I get this job done. I'll post my results.

 

I think the power windows use a circuit breaker. It is thermal and if it overheads it will open and then it will cool down and make contact again. They do wear out. I think I remember them being in the fuse block. This may or may not be the same thing you guys are referring to as a relay. The factory shop manual schematic will show it.

 

The circuit breaker feeds the isolation relay. The relay is used to prevent window operation unless the key is in the RUN or ACC position. The relay is located behind the driver side kick panel.

 

Makes total sense and either the circuit breaker or the relay could cause the problem. I would check the circuit breaker before I pulled the kick panel.

 

That is correct - I have used a test light to confirm that I am getting power on the output side of the circuit breaker (that is in the fuse block). I have also used the test light on the back of the master power window switch and there is no power there (this was done with the ignition key in the on position). The car has only 140,000 miles on it and after its first five years, I only drove it occasionally in the summer. The corrogated rubber wiring cover (running from the driver door to the body) is intact and shows no signs or wear. I'm betting the relay (behind the kick panel is the problem) - we shall see. Thanks all.

 

I would bet on the relay. If it is not a wiring problem it couldn't be much else.

 

​​​​​​​​​​​​​​I know some of you get tired of my stories of back-in-the-day when I was installing stereos but I encountered this once because I ran new speaker wires inside the factory wiring boot of a Chevy pickup and that speaker quit working in less than a year. When I diagnosed the problem I pulled the wire out that I had installed and found the wire broken so cleanly that it looked like it had been cut inside the insulation. The speaker wire insulation was clear so I could clearly see the separation of the copper wiring inside. After that I always put a twist in the speaker wiring I ran through the factory wiring boot and never had another problem. Dunno if it was the change I made or just a coincidence. Now back to your regularly scheduled programming...

 

I don't, because those stories are experience speaking. We can always learn from others' experiences.

Heard it said once that experience was what you got when you didn't get what you wanted.

The "offset" wiring conduits are better than the accordion style, but not by much. 64 Starfire and 69 Toronado both have offset conduits and I've had to repair PW wiring in both.

 

I too was a car stereo installer for years. Saw so many electrical hack jobs.

You think electrical problems suck? I passed once on a 60 Cadillac four door that was loaded. Reason? Huge huge amounts of vacuum lines powering everything. I thought oh hell no.

​​​​​​​Original poster you are on a good track. You have gotten smart advice.

 

Update on my power window repair - yes, it was the relay behind the driver's kick panel. Just need to replace the master power window switch now since left rear quarter window won't work using the master switch (its own switch works though). While I have everything apart I lubricated the vent door cable connection. Does anyone know how to access the upper vent door so it can be lubricated too??