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Dr. Hamman
Dr. Hamman, Technician
Category: Classic Car
Satisfied Customers: 6286
Experience:  I have 30 years experience repairing, restoring, and customizing cars, and pickup trucks.
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Ford Mustang: Headlights and parking lights pulsating with

Customer Question

Headlights and parking lights pulsating with or without engine running
Submitted: 1 year ago.
Category: Classic Car
Expert:  Jeremy replied 1 year ago.
Hi! My name is ***** ***** I will do my best to assist you with your concerns.
What do you consider as pulsating? Lights go from normal to dim back to normal rapidly or the go from on to off and back on?
If normal to dim and back to normal, check the light switch to feel if it is overheating. I've replaced a few of them overheating and doing that.
If going from on to off and back on, check the relay for it is usually the cause of that.
These are based on the info you provided with the engine off.
Let me know what you find.
Customer: replied 1 year ago.

The pulse is from normal to dim also I can hear a soft ping each time they dim. I installed a new switch, head and parking lamps. Being that it is a 65 Mustang I also converted to an alternator with a built in regulator.

Expert:  Jeremy replied 1 year ago.

I was thinking newer Mustang since it was posted in this category. It could be a different scenario on the classic. Let me opt out and request this to get out in classic car. There is an engineer over there, Dr Hammanvor something like that. I can't remember his name, but I know he is extremely good with the classic cars and he'll be able to guide you on exactly where to look. If I'm not mistaken, he retores these for a living and he may have had the exact problem you're having before.

Expert:  Dr. Hamman replied 1 year ago.

Hi, I am a professional certified mechanic, with an engineering background, and 35+ years experience. I will do my best to assist you. Also keep in mind I don't know if you are a pro or a novice, so feel free to add any additional info at any time.


I am an electrical specialist, and I have worked on a lot of these old mustangs. Are the headlights going off and on, or just dimming. And have you been able to locate the sound.

Customer: replied 1 year ago.

Dr Hamman I replaced the light switch as you suggested. I still have a flickering of the headlights about 2 per second. I also can hear a very faint buzz sound and I can feel a very slight vibration in the light switch when they flicker. The light switch does not heat up.

Expert:  Dr. Hamman replied 1 year ago.
Have we worked on this in a previous post. I was reading my last post, and it seems like we got out of sync on this.

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