My headlights will only come on when the dimmer lever is held in the "passing flash" position. The front parking lights do not work either. All other lights work and when the headlight switch is turned on the warning bell chimes as it should but no lights. The "auto" position for headlights does not work either. Turn signals and 4 way flasher work and all fuses are good. The headlight switch has no apparent defect. Any ideas for where the problem is?