Hi I need to determine if problem is the door switch or light itself. light works fine when i turn the light on manually. It does not come on when either front door is open. any help at all would be appreciated.

Unless yours has been modified or broken, most German interior lights have a 3 position switch with "Always on", "On when a door is open", and "Always off" as the three options. Maybe yours is just in the "Always off" position (which is useful when you've got to work inside the car with a door open for a long time).

thanks yes I am familiar with 3 position switches. My interior light once worked that way but right now it is only a 2 position switch as it does not come on when the door is open.

I think your problem lies in the time delay relay, which actually turns on the light when one of the door switches is made. Earlier models just worked with the drivers door switch but later models incorporated a time delay which kept the dome light on a few seconds after the doors were closed and locked.

On my 79 300SD, the relay is mounted on the firewall, behind the dash cluster.

Jim

I had a similar problem with my 94 E320 until I realized that the light I was switching on and off was the front passenger reading light. There are 2 bulbs in this overhead lamp, and bulb for the interior light (the light that comes on when the front doors are opened) was burned out. Could this be your problem?
Mark

thanks but that isn't whats going on here. There is just one bulb here. Hopefully someone will help me who knows the 1984 123 chassis

thanks I think that you are likely correct. You say that it is behind the instrument cluster? Do you mean behind the speedometer tach etc?

I had the same problem with my 1995 E420...interior light stopped coming on when door opened. I checked all fuses, then bought a new door plunger switch from the dealer, which I thought might be the problem. Didn't help. I got lucky, however, when I pulled some of the plunger switch wiring out through the hole and found where several wires had been joined together by twisting them and taping. The electrical tape had come partially off and the wires were shorting against the body. I retaped it properly and no more problem. May not be your problem though.