FLICKERING HEADLIGHTS
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New User
Joined: Oct 2001
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FLICKERING HEADLIGHTS
My headlights seem to vary in brightness when on. I can't seem to find anything in the wiring that causes it. I have put another alternator on and still have the problem. Any ideas what could be causing this? Thanks
Elder User
Joined: Aug 1999
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FLICKERING HEADLIGHTS
I had a problem like this last winter one weekend. It was an exposed hot wire that at one time went to a license plate light, shorting against the frame of the truck until I figured out what was happening and insulated it. I have an aftermarket voltage gauge that was diving down ever time the wire touched the frame of the truck. I'd say if you have a frayed wire that's shorting I'd give it a great chance of being very close to the end of the truck. Check around especially around the rear bumper. I saw mine arcing.
BBT
BBT
Posting Guru
Joined: Jun 1999
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From: Comox Valley, Canada
FLICKERING HEADLIGHTS
Is it just the headlights, or all the lights as in dash, dome etc?
If all lights it could be the voltage regulator or corroded wiring between it and the alternator.
Also could be a loose/worn out alternator belt.
Sparky
If all lights it could be the voltage regulator or corroded wiring between it and the alternator.
Also could be a loose/worn out alternator belt.
Sparky
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New User
Joined: Oct 2001
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FLICKERING HEADLIGHTS
Yes it is the whole lighting system, dash lights ect. I never thought about a license plate light. Will check that out. I was wondering about the regulator or relay? I don't have any charginging problems though. Thanks
Postmaster
Joined: Apr 2000
Posts: 2,838
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From: SD
FLICKERING HEADLIGHTS
[font color=red size=2]I had the same problem with my '73 F100 a couple years ago (all the lights flashing). It was a bare wire. At the back between the bumper and rear fuel tank, the wires go through a cross member, it had rubbed the wires bare and was shorting them out. I repaired the wires and covered them with a piece of rubber hose, haven't had problems since.
Marty
"Cleverly Disguised as a Responsible Adult"[/font]
Marty
"Cleverly Disguised as a Responsible Adult"[/font]
Lead Driver
Joined: Nov 2000
Posts: 6,624
Likes: 342
From: Albuquerque
FLICKERING HEADLIGHTS
I have noticed my interior light "flashing" when at idle. It's not real noticable. I believe it comes from the voltage regulator switching in and out. Any bad connections would accentuate this problem.
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
1977 Ford F-100
400m/c6/4:11/Gear Vender O.D.
Crane hydralic roller, forged, ported polished,Deamon,Edlebrock, yada, yada, yada
280,000 miles
Stock on the outside
modified/rebuilt everything
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New User
Joined: Oct 2001
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FLICKERING HEADLIGHTS
I have what seems like a related problem that I can't figure out.
Whenever the electrical draw is too high (e.g., headlights on), the engine doesn't run smoothly at anything more than an idle.
ANybody ever experience something like this?
Thanks, J
1978 F-150 351
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Joe Kucinski
Senior User
Joined: Sep 2001
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FLICKERING HEADLIGHTS
Well, about the headlights- Had the same problem and it was a bad taillight bulb shorting back into the system. Another characteristic of that is when every light turns on when the taillights are applied. So maybe it's not a problem for you but - just another angle on the situation.
In response to BIG_YELLOW - I have a Jeep that did the same thing (this 72 Jeep has the same wiring layout as a Ford would)
Well turns out that it would draw so much that it would weaken the ignition system. Just a charging problem. Check your alternator, regulator, alternator belt, and battery.
In response to BIG_YELLOW - I have a Jeep that did the same thing (this 72 Jeep has the same wiring layout as a Ford would)
Well turns out that it would draw so much that it would weaken the ignition system. Just a charging problem. Check your alternator, regulator, alternator belt, and battery.
New User
Joined: Jul 2001
Posts: 8
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FLICKERING HEADLIGHTS
a quick test to see if the reg is bad. start up you truck and take the ground off the bat if it dies the reg is bad.
i have 75 3/4 seemed to charge fine never went dead but with lights on at night light dim and get bright. put new reg on no problems.
i have 75 3/4 seemed to charge fine never went dead but with lights on at night light dim and get bright. put new reg on no problems.
