1988 S4 Headlights

[Martin1]

My headlights have developed a bizarre problem. They began acting erratically and not going up or down reliably (freezing part way up or down but not consistently). I made the assumption this was a relay problem and replaced it but the problem is worse now. The lights now will not go up at all. If I manually wind them up and turn on the ignition, they go down every time and completely but if I turn the switch on and turn on the ignition, they stay up but don't light. I took the cover off the old relay and, if I close the relays manually, can make the lights go up and down. The side lights and the fog lights work normally.
Can't think how this is related but my passenger seat electrics have failed at the same time. None of the switches work.
Any help would be greatly appreciated as I've done tons of checking of connections and fuses and tracing the wiring diagrams but haven't got anywhere.

[Martin1]

Hi all, been working through the wiring and electrics this morning and it's gotten weirder!
So, sidelights work fine, fog lights work fine, no brake lights, headlights will not go up, do not illuminate when wound up, go down when switch turned to off after wound up. When turn on headlights (switch to position 2) fog lights go off, HVAC fan stops. When brake pedal pushed, no brake lights, fan goes off. When brake pedal pushed, relays IV (ignition relay X) and VIII (defroster relay) click. All this engine running or not.
Is there an obvious place where all these circuits come together? I've been poring over the wiring diagrams and am having trouble finding a common thread. Is it the ignition switch? Light switch?
New to forum, any help greatly appreciated.

[Danglerb]

Time to clean all of the ground points, pull and reinsert all relays, clean fuse contacts, etc etc.

[LummoxPG]

Hiya Martin...I have an 88 and I couldn't agree more with Danglerb's advice...I had some odd stuff going on... I cleaned all the ground points ( well 8 of them ) pulled the fuse panel and cleaned it thoroughly with deoxite...ordered new oem relays...and put in quality bussman fuses (nothing Chinese). It made a huge difference...windows and sunroof opened and closed much faster and curious HVAC blower issue resolved itself. Just do it.

[Martin1]

Thanks guys, I'll get started on that today.

[GabrielS]

Also consider the switches around the instrument cluster and center console. When I experienced erratic lighting of the instrument cluster, I removed the rotary dimmer switch under the dash and found it had green corrosion on the contact points. Cleaning it with fine grit sandpaper then treating with DeOxit followed by dielectric grease solved the problem, the instrument lights were now stable and dimmed properly. Something to consider is pulling the instrument cluster and checking and cleaning all connections, they seem to have a tendency to corrode causing havoc.