1987 300 SDL headlight switch light replacement
 

Hi All, I recently started really trying to restore the interior of my 1987 300SDL and I noticed that the light on the headlight switch is missing. I am having trouble finding the correct light. I have two switches from MB both share the same style female end for the light to insert into. Attached I have a picture of where the light should be inserted into. A part number or a link to a site that sells the light would be greatly appreciated.

Here is the image

I'm curious if the SDL's ever had a bulb installed. Mine is missing too and doesn't appear to have ever had one. Seems like a strange thing for someone to remove...

I know that all of the w126s had lights in the switch.

Pretty sure that is for rear fogs as an indicator they are illuminated...something the US market did not receive thanks to our awesome DOT laws.

I know they had the fitting, but whether or not they were used is my question. The wiring diagram for the car does not show an illuminator bulb in any of the prints which is why I question whether it ever had a bulb fitted or would be used if one were fitted.

You can drop a bulb in there but IIRC a DOT switch isn’t wired to illuminate it. Check with a voltmeter.

Sixto
98 E320s sedan and wagon

So I just got home and check the G wagon with the same light switch but it is a euro spec. Here is the image. Im not sure if mine is missing the plastic piece or it was not on the w126

The American spec 123/124/126 cars of the era (1980s and prior) use the same switch assembly as the Euro spec. The bulb is to indicate the rear fog light is engaged by pulling the switch out to the second detent. If you hold the knob up to the light you will see the orange dot is really a lens.

However the US laws did not recognize a rear fog light until some time in the 1990s. I know my W210 and all my newer cars have a functioning rear fog light but neither the 87 300TD nor the 83 240D had the light.

In the US on the 80s models they omitted the wire from front to back that powered the rear fog light bulb. Also the socket position is empty in the left rear bulb holder. Finally the terminal 31 (ground) on the light switch does not have a wire installed going to ground, which means the bulb has no ground path. Therefore pulling the switch out all the way does nothing on a US spec car, even if you put a bulb in there.

So if you wanted the rear fog to work you would have to do the following:
- rework the rear light assembly so that the bulb position is populated. Some cars the socket is there but not wired, others there is nothing there at all and it has to be retrofitted.
- run a wire from front to back for the light power
- run a ground wire to terminal 31 on the light switch
- Install the little bulb (same bulb as the vent wheel lights) in the switch.