Bulb out warning light/rear right marker light out

[FranGuy]

Hi All,
My right rear marker light is out (the one that you turn on by twisting the headlight nob to the left) and the bulb out warning light comes on when i turn the knob to any position. Easy fix right? The bulb for that light must be out.. well thats what I thought. The bulb for the rear marker light is the same middle bulb in the bottom row of the light panel, not counting the little bulb all the way on the outside. This is the same bulb that is used for the rear running lights.


Im talking about the light in the middle read square in the photo.

I tested the other lights that activate that square, and they work fine! Same bulb works in that case. So my question is what could be causing this? Is it the switch up front? or is there a special bulb that is needed? I saw a couple threads about a LCM, but they didnt really explain what is was. I didnt have my multi meter when I tried replacing but measuring the voltage is the next step.

Thanks in advance

 

[TerryA]

@FranGuy,
Not sure which light you’re talking about but if it’s the EXTRA BRIGHT FOG when you pull the light switch FULLY OUT. To the best of my knowledge it’s ONLY on the DRIVER’s SIDE. There is NONE on the RIGHT SIDE.

Weird but thats the way it’s been on all 5 Benzes that I’ve owned.

 

[emerydc8]

When you test the socket, if you only get a few volts there’s a good chance it’s a lamp-out control monitor. If you don’t have a spare, now might be a good time to buy one before they dry up. I’ve bought a few on eBay this year for $35-$50 inc. shp. It’s easy to access in the relay box right behind the fuses.

 

[FranGuy]

For clarification I’m talking about the light that only comes on if the keys are off and the headlight knob is turned one click to the left. But good intel about the light control module. I’ll look into that.

Also great intel about the fog light. I was also confused about that

 

[emerydc8]

I’ll have to check the turn to the left position. So it doesn’t illuminate for anything else?