By December 7, 2006 3 Comments Read More →

Headlights Flicker – Alternator Problem?

I had to replace the alternator on my F-250 Super Duty Diesel last year. I now notice at night that the head lights and dash light pulse. Is there a problem with the alternator that could cause charging problems. I just had to replace both batteries and wonder if there is a charging problem as well.

Thanks you

Hi Michael,

Yes, you could have an alternator issue. The voltage regulator is part of the alternator and a common symptom of regulator failure is flickering headlights. Sometimes the connector at the back of the alternator will overheat and melt, so check that first.

Most alternator repair shops can replace the regulator for you (assuming the rest of alternator is still good) , so you don t have to buy a complete alternator.

Take the truck……not just the alternator to the alternator shop for testing. Testing the charging system ON the vehicle will make sure you don t have a wiring or bad ground issue that can be overlooked if you removed the alternator yourself.

BTW, the main culprit of alternator failure is a weak or bad battery. The alternator works overtime trying to keep a weak battery fully charged. It would not surprise me one bit to find your alternator worn out in one year’s time due to running with weak batteries. I provide free battery “load” testing during routine oil changes for my customers who drive these 2 battery set up diesels. Talk to your local mechanic about checking your batteries more often….every 6 months would be perfect.

Austin Davis

About the Author:

Austin Davis, consumer car repair advocate. "Hi there! I love to help people solve their car repair problems and I hope my site was helpful to you today. Thank you for stopping by."
  • Austin Davis

    Same problem with headlights flickering as in the article??? Tell me what is happening, or not happening and we can start ruling things out.

  • Julio h

    I have problems with charging system I replaced the alternator and battery, and i still have the same problem

  • Doug

    I have the same problem with my 2001 Ford F250. Could you please let me know if a new alternator solved your problem or what you had to do to fix your problem?