300d 1984

1. With fuse 1 in when i put the lights on the fuel and temp guages jump to three quarters.

2.with fuse 1 out the instrument lights are off ; the guages read ok when i switch the lights on BUT when i use the turn signal or the hazard light the guages start jumping again.


Where do i look???
would appreciate some help.
regards

I found this post on a search. I am having similar problems. Everything works fine until I turn the lights on, then guages go nuts and instrument lights go out as I drive. When I come to a stop they com on again. Did you ever fix your problem?

I had very strange gauge and other electrical problems on a non-Mercedes vehicle once. To some extent I attribute the previous owner selling the vehicle because of this because the altenator light stayed on all the time.

It was a short in one of the dual-element turn signal bulbs. When one of the filaments broke, it fell down against the other filament. This created an electrical issue because power would be applied when and where not "expected" by the system.

A simple inspection of all your dual element bulbs is a cheap attempt at a fix. I think in most Mercedes only the front turn signal bulbs are dual element. Take them out and look for a broken filament that might be fallen against the other filament.

Man, I hope this is it.

Ken300D

Thanks for the info. Stayed up most of last night troubleshooting the problem. Couldn't see driving to church tonight with no dash lights. Found a bad ground wire. The terminal lug had broken off. When I pulled the cluster the wire was not attached to anything. I re-grounded it and everything went back to normal. Just wish it wasn't 25 deg and dark, but a 100w bulb in the trouble light makes for a good hand warmer.