No Cluster lights!

[e30vert]

Well, Ive got a strange one.

I was testing the wires that hookup to the Ashtray Lighter and illumination (I think there is a light in the ashtray?)

In any case I used my meter to determine that there was 12 volts on one connector and then checked it by using the Red/Yellow wire as I thought it might be a source of ground. Nope. The Brown wire next to it was Ground. All was well or so I thought.

Then I started the vehicle and pulled the light switch all the way out. The light for my on board computer turned off and my cluster lights did not turn on.

I pushed the Light switch to the off position and found that the On Board Computer light turned ON ! WTF?


I figured it was a fuse. Pulled EVERY fuse out of the panel and checked each one by one for continuity between the spades. Each one DID HAVE continuity. Put them all back in their respective places.

Grabbed my Bently Manual to see if I could track the issue down.

On page 24 of the Electrical System section it indicates that I should pull the cluster and check certain pins on the connector that goes to the Cluster.

Anyone have this issue before and have any insight?

[e30vert]

Well after a shitload of ripping my vert apart I think I have the issue tracked down!

Its funny how after you find what you think is the source of the issue and backtrack it in your mind it makes perfect sense, but when trying to think of a reason that the issue is presented it is sooooooo elusive.


I probed many points on C204 (under left hand side of dash) and C103 (under left hand side of dash) this lead me to determine that I was not getting any 12 volts present after the headlight switches built in dimmer module. The voltage on the output pins of the headlight connector should show some specific voltage on pin 2 which goes to the dimmer circuit in the cluster lights and also the HVAC control lights. Starting with about 12 volts as all of the voltage drops across the internal potentiometer and then decreasing as the headlight switch stem is turned to decrease the glow from the lights in the dash and HVAC controls.

To determine that the potentiometer was truly bad within the headlight switch I took apart the switch and measured across the switches terminals for a chance in resistance. There was no change when I rotated the headlight switches stem and there should have been!

So now I need a new headlight switch or just the potentiometer part. :) Gonna post up in the WTB section. If this resolves the issue after installing a new headlight switch I shall update this thread.

[Cinnabar325is]

So did a new headlight switch fix your problem? I'd love to know cause the same exact thing just happened to me today. I pulled out the headlight switch knob and the headlights went on, but the cluster lights and OBC lights went off. When I pushed the knob back in, the OBC lights turned on again.

[e30vert]

Yes. Just grab a headlight switch from the Pick and Pull or Pick a Part salvage yard and you will be set! There are 2 different styles so be selective. The backs are different even though the fronts look the same. Perhaps pull yours and take it with you in your pocket so that you can compare. Good luck!!!

[khalild]

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