The most common cause of sudden headlight failure is the dimmer switch. It lives in a very nasty environment under the floorboard, and it's not uncommon for the switch itself, or the connector to corrode to the point the lights get intermittent or go out altogether. With the headlight switch turned on, one wire at the dimmer will be hot, and the Hi/Low switching goes from the dimmer to the headlight harness.
Jerry

Edit- - - - -switch up and down from Hi to Low a few times and see if the lights flicker or comer back to life.
Jerry


Last edited by Hotrod Lincoln; 01/30/2010 8:51 PM.
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