I can only speak for my 190e. The parking lights and the headlights turn on by turning one or two clicks clockwise. If I pull the headlight knob out once, the fog lights in front come on. One more pull, and the fog lamps in back come on in addition to the front ones.

For my car, the fog lamps do not come on automatically when the headlights come on. You said that the knob is in the innmost position. Maybe there is a wire shorted out in the knob or something like that? I'm not too technical, but thought this might be helpful to start you off.

Thanks.