Voltage drops and comes back
I noticed that my headlights almost cut out and then comeback to full for a half
second. The volt meter goes flat and then comes back in that same half
second. I thought it was a alternator but I noticed it will do it with the engine off
and electrical on...
There sounds like a ground wire is not making a good connection. I would start at the headlights and trace back looking for any ground wire, take it off or apart and clean the connections. I would do this with the ground cable on the battery, and from the grounds on the engine, and make sure you get the one that runs to the body.
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