[MichaelSchidek]

Hello everyone, I've purchased 1984 MB 300SD back in Oct. 2008 and I love the car, but it needs some serious TLC. The odometer didn't work, but the guy had all the records and even a hand written journal recording all the trips. The car showed 204,000 on the odometer. The Journal showed 214,000. When I bought car the dome light didn't work. Went to the Junk yard, found another one that looks new and now the Dome light works like it should But the rear dome light does not. I took it apart and found the light bulb wasn't connected. I connected it, now it just stays on.. constantly. I pulled the bulb so it doesn't drain my battery. I went about my business and fixed several of the more important issues. Vacuum, Brakes, rotors, etc. So now I'm back to the interior lighting. I found that the rear passenger door didn't have a bulb, and the Drivers door doesn't even have a bulb fixture. Something tells me I have to replace the rear bulb and the drivers door bulb fixture and bulb to complete the circuit. But the rear dome light stays on unless I pull the bulb or plug. And so do the passenger side doors. Their lights just on when I'm driving. I was hoping someone might point me in the right direction. I'm hoping someone who knows this stuff will say install a new fixture and bulb and the problem is solved. But I also have a rear dome switch and that doesn't work. Maybe when I put a new bulb and fixture it will? Also the gear selector lights are not working, nor is the vent gauge (part that lets you select how much air to let in the cabin.) lights which I heard is fiber optic isn't working. Could anyone shed some light on the subject? I'm running out of options.

Thank you,

Michael Schidek

 

[AzimuthAviation]

Is the switch on the central panel pushed on for the rear lights? Other than that, I'd suspect a shorted door switch in the rear.

 

[MichaelSchidek]

All interior lights except for the Front Dome light will not shut off

I thought that maybe because I was missing light fixtures and lights in the door that would be the reason my lights stay on. I got another rear dome light switch and under door light fixtures w/ bulbs. I plug everything in, replaced rear dome light switch in the panel next to power sun roof. Same symptoms, Rear dome light stays on, all 4 doors stay illuminated. I'm stumped. Looks like its back to the drawing board.

 

[MichaelSchidek]

Door switch

Thanks, I will take a look at my rear door switches.

 

[Gene Horr]

Also check the central front dome light panel. I am assuming your model is the same way in that all of the interior lighting except for the rear reading lamps and the vanity mirror lights go through the circuits in this module. It is far more than just an on-off switch. The ones I've seen fail safe (no lighting at all) but my experience is only for a few units.

 

[B71ZZZ]

If I remember the circuit goes something like this: from the rear light switch on the center panel 'the power' goes to the LR/RR door lights and then to the rear light.
With the rear doors closed you shoud have power on both sides of the door light bulb terminals and then when you open a door one end of the bulb is switched to ground. I would check the switches on the B-pillars (there's a pigtail connector that can be incorrectly installed) and the front passenger floor for water damage.
Looks like somebody tried to fix it and gave up. Good luck!