1. Remove the covers from the steering column and locate the 14 cavity connector at the combination switch and verify there is good battery voltage on the Red/Green wire. If there is not look for a wire problem or fuse box problem.
2. If there is voltage there then turn on the switch and the contacts in the headlight switch should connect the Red/Green wire to the Red/Black wire and light up the taillights and the dash lights. If there is voltage on the Red/Black wire look for a wire harness or connection problem. If there is no voltage jump the wires and if the lights work the combo switch is faulty. Hope this helps