You probably have a bad dimmer switch. That's a chronic problem on older GM products, cars and trucks. Disconnect the 3-wire plug at the dimmer and use a jumper wire to bypass the switch. There should be one hot wire from the headlight switch, and a high beam and low beam wire. The headlight switch has a thermal circuit breaker built into it, so the lights will flash on and off, not quit entirely, in case of a short.
Jerry


Edit: The older switch might have screw-type contacts instead of a plug. Troubleshoot it the same way, with a voltmeter or test light, plus a jumper wire. Find the hot lead from the headlight switch, then use the jumper wire to bypass the dimmer switch.
Jerry

Last edited by Hotrod Lincoln; 07/25/2010 3:58 PM.
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