I am the proud owner of a 1985 300D Turbodiesel and I have a strange problem for those who may know what is wrong. At night the car starts fine and dash lights come on dim but useable. When I turn on the headlights the lights get dimmer and the tempature gauge and the fuel gauge go higher than they really are. Turn the car off and on and the gauges are fine till the healights are turned on again. The only dash lights are the turn signal lights and the seatbelt light that won't stop going off every minute or so. Before I open the dash up I thought I would ask the experts.

1985 300D Turbodiesel
1985 BMW 528e
1993 Chevy Suburban
2003 Pontiac Montana (Mommymobile)