well I've had this problem since I bought Raptor in Oct. '04. The lights always flickered while the ignition was on...my voltmeter went bananas, but when I took out the headlights it all stopped...any clues? Also I found one wire that was maybe factory splice pink or red wire with stripe that goes to the lights either the high or low beam...both lights off the same wire....my ground wire from the solinoid to the block was had...other than that I dunno
Your alternator might have a dead phase, or your voltage regulator might be wonky, and the problem might not be showing up until the alternator is under load...
got a new alt. and the voltage red. is on the back I believe...if so that is new
hmm your regulator should be on the right fenderwell behind the battery
5.0 cars from '86 have the internal regulator alt..
for some dumb reason I thought he had an 84, guess I should have checked his name! lol
I realize this might sound stupid,but what about the ground strap between the engine and firewall?I did an engine swap in a tbird in the past and had a few different light problems,until i replaced the ground strap.