Headlight wiring copied from the sticky. Low beam headlight on tan, high beam light green. They share the same ground. The only thing I can figure is a defective ground on the passenger side. Low beam passenger bulb is getting ground thru the high beam filament in the driver side. Turn on the high beams, you now have power on both filaments on the passenger side (no ground) and since the drivers side has an intact ground, the high beam works on the drivers side.