1978 98 no lights
 

Little while ago the low beams quit working, the recently the high beams stopped working have tried a new switch but not dimmer replaced driver side low beam no change cannot find wiring diagram to test voltage probably will try dimmer tomorrow because I think it might have gone out today because of no high beams anymore.

use a 12 volt tester an see if your getting volts to the lamp, then chase back the wires intill you find the dead wire or switch.

Did you check your fuses and relays?