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Power Window wiring?

Posted: Wed May 30, 2018 7:43 am
by waltb
So on my 1980 528i the power windows have stopped working. They starting going intermittent for the last few days and then they completely died. There is no power input to the two little breakers underneath near the steering column (feed by red with green stripe wires if I recall). To get the windows back up last night I just jumped 12V to the input of the window circuit breakers and the windows went up fine. So the problem is the power feed. So looking in the Haynes manual there looks to be a upsteam relay (plus a few intermediate connections) in the feed circuit. But I do not see any window relays under the dash or in the fuse box.

Since I do not see any power window relay in the fuse box itself I presume the window power relay is one of the relays hanging off of the side of the fuse box? Can anyone confirm this and if so which one is it? I will start debugging further when I get home from work.

Oh and everything else seems to still work in the car (sunroof, fans, lights, rear window defogger) so the problem seems to be isolated to the power window system.

Walt B.
'80 528i

Re: Power Window wiring?

Posted: Wed May 30, 2018 5:41 pm
by waltb
I am going to post my own answer for posterity. I found the relay that powers the power windows. It is located under the dash on the side of the junction block near the hood release lever. In my case the relay was working fine. However It was not getting any power. At least in my 1980 car, the red wire from this relay goes into a black sleeve and independently through the firewall, runs along side the main wiring harness, bypasses the fuse box, and is connected directly to the battery + post. Sometime in the past this wire was spliced near the battery. Probably because the + post clamp and wire to the starter was changed and probably by me many years ago since I have owned the car for 29 years. That splice was wrapped in tape so I could not see it. I tracked the lack of 12V back to the splice and unwrapped it. It was one of those crimp type splices and the wire pulled out of one side but this was obscured by all the tape. I soldered it this time (as I don't like those crimp type splices anymore), heat shrink wrapped it, and full power has now been restored to the windows. Fun tracking things like this down.

Walt B.