Actually, I believe the green dot on the headlight switch is only illuminated when the fog lights are on. If your car is fitted with the factory fog lights once the headlights are one, pull the switch out one notch. That should activate your fogs and illuminate the green dot.
The second notch out is for the rear fogs, which I don't believe your car has, unless it's a Euro model. Most of the newer Benz's sold in teh States have the rear fogs as well (the rear fogs only light one side of the tail lights brighter, usually the driver's side).
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.