I'm not sure if your car is like mine or not. I purchased my car without any manuals and ran into the same problem. I read here that the odometer trip button, center of dash, I was using to reset the odo is also the dimmer switch on a 1982 300D. It may be the same for yours. I sure laughed hard when I found this out having opened the dash many times trying to get the lights to work. Good luck.