My Car Headlights Dim at a Light or When I Have the A/C on – Why?

Reader Question I have a 1965 elcamino with a 350. When I drive at night, the headlights pulse. Its not too bad untill I stop at a redlight, and they really start to pulse. When I turn on the Air conditioner, wipers or radio, it looks like im flashing my lights. What do you think?
Thanks, John

Hi there John

Thanks for your email and your question. I would suspect you have a faulty voltage regulator, which should be located on the passenger side inside fender under the hood IF no one has converted this engine to use an internally integrated voltage regulator – if it has then it would be located inside the alternator itself and the alternator should be rebuilt or replaced with a rebuilt unit.

Look to see if you have an externally mounted voltage regulator on the passenger fender and make sure that there are wires attached to it that go from the alternator to the battery. If so, you can buy a regulator at any auto supply shop and replace it yourself, just make sure you hook it up exactly as the old one.

I would also inspect the battery cables to make sure they are good and tight and clean. If a cable is loose or corroded it could cause electrical problems as well. We get more cars towed into our shop with dirty or loose battery cables than any other kind of “no start” problem.

Also make sure your alternator belt is good and tight and not slipping…which you should hear a high pitched squeal noise. A loose belt will not turn the pulley on the alternator fast enough to produce the electricity needed by the battery.

Keep me posted as to what you find out.

Blessings,

Austin C. Davis