My headlight go down when using the down switch in the cab (from 0 to -3) although it shows position 3 not -3. I can drive them up to 0 again but not up beyond that point. If I disconnect the headlight connectors I get the same results, implying that it is the control system and not the headlights units. I am hoping it is a simple fuse somewhere but cant seem to find and useful wiring diagram. Help..!!