Like the title says, My g/f's car is a 1987 ford thunderbird 6cyl automatic. It has the digital dash (speedometer etc.) When she turns on the headlights the dash turns off so she cannot see her speed. She told me a mechanic told her she has a bad switch. Im moderately mechanically inclined but im unfamiliar with her type of car so im not exactly what "switch" im looking for. Any information on what im looking for, or a good way to diagnose the problem to be sure would be appreciated. Thanks guys.