New day, new thing to help my grandson with on his 1990 240 DL. None of the instrument panel, transmission gear selector, or center panel lights are working at night. there is power to the seat belt warning lights and the ash tray light as well as the glove box light. Fuse #16 was tested and is good. Looking at the wiring diagram it looks like the instrument panel light rheostat may be the culprit. I do know turning it has no effect on if the instrument lights come on. I pulled it out and tested it with an ohmmeter. The reading ranged from a high of 650 ohms to a low of 630 ohms when the **** was turned but it was not a smooth transition, as the readings jumped around a lot when it was turned.

Any insight or suggestions before I try to find a replacement? With the rheostat pulled out I am going to try and feed 12V directly to the brown wire in the harness to see if that turns on the lights.

Thanks

 

Just bypass the rheostat with a 3 way spade connector - have done that many times.

That wire sends power to two bulbs in the cluster, a bulb above the rocker switches, (that dimly illuminates them) bulb on the fan switch and the heater slide. Don't remember about the shift indicator.

Glove box is on a different circuit and where is this ashtray light I have no memory of? Oh yes - forgot about the rear ashtray.

Seat belt light is on a different circuit.

It's common to find a whole bunch of bulbs bad on those old cars.