W126 Door Light Switch Trouble
 

Last night while loading the car to return home, I discovered that the front interior lights don't come on when the passenger's door is open. The driver's door switch is working fine and both rear doors turn the rear interior lights on without a problem. I'm pretty sure that the problem therefore is with the pillar mounted switch on the passenger's door.

Has anyone had a similar problem? Is the issue likely with the switch or the wiring? My understanding is that these switches close the circuit to ground - is this correct?

Thanks
jlc

I had a similer problem with dome light,and it was the [seat belt warning relay]

Seat belt relay problem only applies if the lights don't come on with the driver's door open--like my car. The best thing to do is swap the switch with one from another door-easy to do. Then try grounding the switch with a jumper wire if the switch is good. (Make sure it is a ground connection, beleive it is.)

Don't these work just like your refridgerator door switch (normally open)? Pop the one out on the passenger side and connect/jumper the 2 wires together. It's the switch if the light comes on...

door light switch
 

the MBZ door light switch was apparently designed in about 1937--and hasn't been improved. They regularly fail to make connection when they get a few years old. Either 'work them' with contact cleaner or replace--they are cheap--both to buy and quality wise.