headlights flickering
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headlights flickering
My head lights are flickering both of them are flickering at the same time. When the head lights flicker off the side lights come on for a second. I replaced the head light switch it seemed to hold it for longer than it did before ( like 5 seconds longer) than they started flickering again. 1979 ford f250 300 six rw drive custom mostly original, don't think any wiring has been tampered with, anyone know where the head light relay is? Or if there's anything else you think could be the problem? Thanks
Posting Guru
Joined: Sep 2003
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From: Northeast LA
For me it was the positive wire for the front parking light above the drivers side headlight. There was a bare spot in the insulation of the wire at the core support and when the bare spot hit the metal it would cut the lights off. Just something else to check for.
Senior User
Joined: Sep 2006
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From: Atlanta, Georgia
I had that happen while sitting in an hour long traffic jam my engine was fine but there was so much saturating heat. I honestly think the headlight switch got hot. Once I started moving good again issue went away.
460/c6 / longtube under the cab headers / pulling a 18ft car trailer. Was on my way to pick up my other truck that broke down on my Dad returning from out of state.
460/c6 / longtube under the cab headers / pulling a 18ft car trailer. Was on my way to pick up my other truck that broke down on my Dad returning from out of state.
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I heard some times the relays in the old light switches sometimes can't take the full load of all the running lights so I offed all the side lighting onto blinkers and brakes, (was planning on it anyways the side lights didn't work at all before) and I turned the head lights back on and they worked for about 15 seconds before they started flickering again I checked the voltage across the battery it looks fine, guess I'm off for a voltage regulator tomorrow! I checked all the hidden wiring it looks fine, is the light dimmer switch you are talking about just done by turning the the head light switch button thing? Thankseveryone
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From: Northeast LA
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Oh the high beam switch. But everytime the lights flicker I can hear a noise coming from the headlight switch and it is brand new I replaced it today
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MSEE
Joined: Apr 2004
Posts: 10,386
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From: Austin, TX
What does "looks fine" mean? I asked for a number.
How do you know you know it's the regulator itself?
OK, that changes things. This has nothing to do with the voltage regulator. That's why I stress that you follow my instructions and take measurements rather than randomly replace parts.
How do you know you know it's the regulator itself?
OK, that changes things. This has nothing to do with the voltage regulator. That's why I stress that you follow my instructions and take measurements rather than randomly replace parts.
Fleet Mechanic
Joined: Feb 2010
Posts: 1,742
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From: Near St. Joseph,MO
You should also be more specific on what it's doing.
Is it flickering as in on/off or is it flickering as in pulsing?
Mine pulse when the truck is running, my battery is weak and my alt is going out. I'm planning on fixing these with the 3g upgrade and a different battery as soon as I can get to the junkyard.
Is it flickering as in on/off or is it flickering as in pulsing?
Mine pulse when the truck is running, my battery is weak and my alt is going out. I'm planning on fixing these with the 3g upgrade and a different battery as soon as I can get to the junkyard.
Post Fiend
Joined: Mar 2011
Posts: 8,501
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From: Lynchburg, VA
There's a breaker built into the headlight switch. You've got too much current draw downstream. Listen to fmc; you won't find a much more knowledgeable guy when it comes to automotive electrical systems.