W211 fog lights

[delb0y]

Hi folks

Odd one this, always had lights on auto. Noticed today with on auto headlights are on plus one fog. When I switch to manual and turn on fogs both work fine.
Can anyone advice ?

Thanks

 

[Petrol Pete]

Depending on model when you have a main headlamp bulb blown the fog light below will illuminate 'half effect' to compensate for the missing headlamp.
Some foglamps have a two filament bulb with a 3 wire connection some have a single filament bulb with a two wire connection.
The two are not compatible unless the wiring is modified...ask me how I know .

How you are getting both headlamps on and one fog lamp is still a mystery. Just check if the fog lamp is on 'full effect' of 'half effect' by comparing brightness when manually switching fog's on. Good luck

 

[DrNick]

Anything to do with one foglight lighting up when you turn that way? Were your wheels straight when you looked?

 

[delb0y]

Not sure guys, it's new one on me, I thought the fault has disappeared but few nights ago, same thing happened, one fogs on I had only the headlights on, without turning the fogs on , they shouldn't be on, this morning it seems fine, wheels were not straight but surely that shouldn't matter

 

[Germgh0st]

As said above - if your wheels weren't straight was it perhaps a fog light acting as a cornering light?