E30 Dashboard Lights Mystery

[thecaines]

I'm new to this forum and new to forums in general. Anyway, just bought a 1990 325i 4-door and am working out the bugs. I'm stumped by this one - when the parking lights or headlights are turned on, the dash lights do not turn on. No lights in the cluster, the clock/temp display goes off, and probably some others that I don't even know are supposed to be on yet. The idiot lights, speedometer, tach, fuel gage all work, just no night lights. I've checked all fuses, swapped relays around to check relays, no change. This car has a messy looking CD player installation, which I'm wondering about. Has anyone solved this one? Thanks!

[heespaul]

Yeh, this and allot of other trashed wiring by previous bad alarm install. I removeed the alrm and in your case maybe cd. I put it all back together finding more stuff as i went. the frustrating thing i discovered is the way the wiring is routed. In my opinion, spastic. If you have a wiring diagram, trace the beginning of where the lighting starts. I am not sure but, in the instrument cluster, the lights may be in series which means if a bulb is out then it may affect the others down line. This is speculation only. What I do know is this. I started with the wiring in it's original condition, cleaning up the splices, taped connections etc., and from there things started to happen. I traced the light from fuse box to end point and verified any other items powered from the particular run, completly to the bulb. Complete success. Lastly, check the dimming reostat of the headlight switch. The headlight switch should pop out from it' sface plate by squezzing 2 tabs on the shaft. Remove knob by twisting counter clockwise. Remove underdash cover panel. look underneath and see if this is the same as a 318. Once the swithch is out you will see a round coiled wire with a metal finger which turns when you turn the headlight shaft. If this finger is not making contact then no lights. Good luck. Let me know if you have a diagram. Later Paul

[thecaines]

Well, since ALL the interior lights tied to the dimmer were not working I decided to try replacing the switch, and it worked! Thank goodness because the wiring under the dash is a nightmare! I opened the old switch and saw that all the contact surfaces needed a good cleaning (no way to do that when installed though). My old switch might work now, but I don't think I'm going to take things apart again to find out! Anyway, mystery solved - start with the switch.