euro 500sl light switch question

[jimsclub]

On my 1984 euro 500sl, when I turn the headlight switch clockwise to position 1, I get front and back running lights and position 2 I also get the headlights. Now when I go to postion # 3 & 4 I get nothing. I have replaced all the light bulbs front and back and still nothing. Does anyone out there know what should come on for 3&4. Also between the light switch and the parking brake release there is a wheel with 0,1,2,3 positions on it. What does this wheel do?