Dash Lights
 

I am the proud owner of a 1985 300D Turbodiesel and I have a strange problem for those who may know what is wrong. At night the car starts fine and dash lights come on dim but useable. When I turn on the headlights the lights get dimmer and the tempature gauge and the fuel gauge go higher than they really are. Turn the car off and on and the gauges are fine till the healights are turned on again. The only dash lights are the turn signal lights and the seatbelt light that won't stop going off every minute or so. Before I open the dash up I thought I would ask the experts.:dizzy2:

1985 300D Turbodiesel
1985 BMW 528e
1993 Chevy Suburban
2003 Pontiac Montana (Mommymobile)

Believe it or not.......
 

Check your grounding, Batt.-Chassis and especially Chassis-Engine (near the starter). Also check the alternator terminal strip on the passenger fenderwell.

If those turn up nothing. Read a voltmeter across the battery and see what you get. (possible voltage regulator)

I used to have this exact problem with my (sold) US-300D.

The problem was indeed grounding, amongst other things. Make sure the instrument cluster has good contact with the chassis, as well as the battery being grounded to the chassis. If it isn't a grounding issue, pull the cluster and take it apart. Check the PCB board for any breaks in the electrics. In my case, right by the 14-pin(?) plug, was a seperation in the solder-tracking. Get a nice soldering iron heated up, and fix any breaks in those tracks.. and test with a multimeter.

The most common thing I've seen is poor grounding, and electrical breaks / shorts. Check those, and get back to us with the results.

dash lights dont come on
 

I jsut acquired an 84 300D with just about everything working fine except the dash lights dont come on. I'm talking about the one you dim with the rheostat. Could it be that the rheostat is bad? Can't be all the bulbs are out. Even the lights by the a/c switches dont come on.

Could be: Rheostat (likely for the dash lights), fuse, or bulbs....just go through and check the bulbs/fuses/wires/ground connections etc...

looking at the fuse box and haynes manual, the dash lights do not appear to have a fuse.