I have a 1986 740GLE that when you turn on the headlights, the dash panel lights go out and the headlights don't come on. But, if you turn on the high beams, all 4 lights are on. Replaced the headlight switch with no change. Panel lights and parking lights are working fine in middle position. Going bald fast with this problem!! Any ideas??? Thanks.

 

Wiring at healight bulb.