Interior Light Switch - PeachParts Mercedes-Benz Forum

esm6869 · #1 10-22-2003, 09:03 AM

I have done some searches on the interior dome light switch, but have some additional questions. On my '88 300E, the passenger front door is the only door that will still operate the interior dome light when the door is open. The rear doors have never been able to operate the dome light when opened as long as I have had the car, and now the driver's door switch has failed. I believe the switch also operates the buzzer that lets you know you have left the headlights on after the key is out of the ignition...that stopped working as well.

Where is the relay or switch located?

Is it hard to replace?

Someone must have done this before, there was some information available in the past threads. Your help is always appreciated!

esm6869 · #2 10-22-2003, 01:46 PM

Anyone? Somebody must have some idea as to how to fix the relay/switch. Really want to fix this annoying problem.

csnow · #3 10-22-2003, 03:06 PM

Start by testing the driver's door switch itself with a voltmeter, because that is easy.

Based upon posts, seems that the most likely culprit is the 'seatbelt buzzer relay', which actually performs more functions than advertised.

Bought one, but I have still not gotten around to installing it, so this is 2nd hand advice!

This relay is located behind the gauge cluster, on the right side (LHD), way in the back. Some prior posts even have pretty pictures, if you can dig them up.

Now the rear door deal is a whole other matter!
On my car, the rear doors activate only the rear light. Start with the bulb for this one.

esm6869 · #4 10-22-2003, 03:37 PM

csnow, thanks for the direction to the past posts on the seatbelt warning relay. I tried to get the pics to come up, but those sites are no longer supported, so I have an email into Aaron (300speedyDturbo).

As for the rear light, I have replaced the bulb and the switch on the dask console. No luck. I don't think there is power going back to the unit.

You had mentioned to test the door switch with a voltmeter...what will a good operating switch read? I'm guessing 12v, but I am electrically challenged.

csnow · #5 10-22-2003, 04:59 PM

Yes, the switch gets 12v. Continuity across the switch is obviously important too. You could also jump the switch, and see if you get light. There are 2 switches on mine. I did not figure out which did what, just tested them both and proved them healthy.

Hoping the relay will do it. It's getting darker again...