On a 99 SLK 230 I went to replace the back Fog light socket ( located in the rear light assembly) but I have no power, all the other lights in the cluster have power and work, I have even took the light and socket from the drivers side that does work and still nothing on the other side, seems strange that all the other lights work and not just this one, any ideas?

 

Only the left tail light has a working fog light in the US. Should come on with lights on and **** pulled out to second position. Right light just has the hole, no socket or bulb.

 

For some strange reason MB only wanted the rear foglight on on the driver side.
The holder and the bulb is there on the passenger side but there is no wire connected.
If you check the connector, you will find it empty where it connects to the fog.
In my W123 I made an additional connection and it works fine.
I tried the same with my W203 C200. But when on the rear fogs, the check light warning display keeps flashing in the dash.
So I had to disconnect the passenger side rear fog.
Shan.