On your headlight switch there are a multitude of spade lugs & wires, and if you have the power wire plugged into the wrong lug, things just won't work right. I ran into this on one Pantera, and to straighten it out took parking a second very similar Pantera in next to it and comparing ALL the wires on the two switches. All the various years have slightly different wire colors within their wiring looms so a schematic- while helpful is not always the answer.
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