What's wrong / how to fix faulty headlights?

i had a mustang that done the same thing i had to replace the headlight switch

Most of the time the symptoms you describe are the result of a bad ground. Make sure the ground strap between the engine and the frame is not broken. Make sure the screws that hold the socket in place are tight. Once you have the ground fixed the problem should go away.

The other possibility is there is a short somewhere in the wire to the headlights and the circuit breaker is popping, and then resetting itself. Check the wires from the headlight back to the switch for any bare spots where it might be shorting to ground.

sounds like a bad connection at the headlight bulb. is it both or just one? check for corrosion. then id suspect a loose terminal or a loose ground. check the terminal by wiggling it with the lights on and see if it flickers. if so then id either squeeze the terminal back or get a new pigtail.good luck ill check back for a reponse.

Well in that case id see if they share a common ground or if the headlight module has a loose ground(assuming it has one) You'

ll probably need an electrical schematic. it also could be the headlight switch is worn out and not making good contact internally. maybe try wiggling the switch and see if this does it... its hard to diagnose over the internet so sorry if they seem like a lot of answers.

Bad/intermittent ground, switch, connector, or fuse.

check your wiring there mite be a bare spot and it rubbing on metal . hope this helps