Hello: I agree with other posts. Automotive wiring is about as bad as it gets. At each headlight there should be a ground wire to the sheetmetal somewhere. Remove them, clean and reinstall. Look for a ground strap from engine to firewall, clean both ends of it. Look for any ground wires at all, remove and clean them. When you have a problem like this the circuit is designed to have a particular current path. If the designed path for that circuit is damaged, it will attempt to complete the current path through whatever wires it can find, and there is where the problem comes in. It may not be a ground problem, but that is the place to start.
Good luck
Darryl.
Sunday, January 8th, 2006 AT 8:35 AM