I do not have any instruments or console lights in my 88 560SEL. Fuses are all fine. There are no other electrical problems. I did have the wiring plug on the back of the instruments replaced just after buying the car six months ago. The lights did not work before that and still do not. Where should I check next?

My oil and high beam dash lights always glow unless I turn on the high beams. That could be related.

Thanks
David
88 560SEL
67 European Beetle
69 Conv. Beetle
00 Dodge Durango

All of the dash lights operate thru the varible potentiometer in the inst cluster except the radio & gear shift indicator.

Potentiometer
 

Does the potentiometer connect to the small knob protruding from the gauges? If so there is a good chance that the plug into the potentiometer has come off during work on the dash. Or the potentiometer has failed. The latter seems unlikely. On second thought if the potentiometer is not solid state it could have corrosion. The gear selection light does not work either. However, they could have separate problems. Thanks for you help.
David

The potentiometer (dimmer) is the probable cause. My 240's dash lights stopped working shortly after I purchased it. Unfortunately, I didn't realize that the tripometer doubled as a dimmer. In eliminating what seemed obvious, I replaced all of the bulbs, and the headlight switch (twice). In trying to find answers to solve this problem, I ran into this website (why didn't I find this site first :)). Anyway, I tapped it with a rubber hammer a few times & twisted it bit, & it's worked ever since. The oil & highbeam indicators seem like a separate issue. Hope this helps.

Some of the mercedes models have a separate fuse in the back of the dash cluster (like 190D's with the same modelyear). This fuse (if present) can be blown after an electrical short in the dash lightsystem occurred.
I have seen dash clusters with damaged "prints" (I do not know whether this is the proper word for the plate on which all dash components are soldered to)as well.
The potentiometer does connect to the small knob protruding from the gauges, corrosion however is unlikely.
The gear selection light is easy to replace...just to know for sure if this is the same or another (worn bulb) problem.

I pulled my instrument cluster out for inspection. Previously I said the plug in back had been replaced. I rotated the plug one pin CCW and plugged it back in. The gas, oil and water temp gauges stopped working. However, the dash lights started glowing and the low fuel warning light came on. This had never worked before. I think the MB shop that put the new plug in may have mixed a couple wires.

Does anyone have a schematic of the plug cluster? If I knew what each pin was for I could fix it myself.

Thanks,

My local shop made the repair for me. It was a circuit board behind the dash. The instument lights work fine now.