flickering headlights
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New User
Joined: Sep 2001
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flickering headlights
hello, i have a 1973 f-100 with a very annoying problem;the headlights won't stop flickering.they start after about 5-10
min. of driving and don't stop.they flicker in unison, sort of like morse code.i have changed the headlight switch,the voltage regulator and the high-beam switch.i have also cleaned the grounds for the headlights themselves,but still no luck.if anyone has any ideas i would greatly appreciate it.it would be nice to be able to drive my truck at nite!
thanks-jim.
min. of driving and don't stop.they flicker in unison, sort of like morse code.i have changed the headlight switch,the voltage regulator and the high-beam switch.i have also cleaned the grounds for the headlights themselves,but still no luck.if anyone has any ideas i would greatly appreciate it.it would be nice to be able to drive my truck at nite!
thanks-jim.
Fleet Owner
Joined: Jun 1999
Posts: 24,552
Likes: 74
From: Creedmoor, North Carolina
flickering headlights
Jim, If you have replaced both the light switch and dimmer switch, then I would recommend going after the grounds next. Clean them all on both ends of the truck. You can see the head lights flickering but not the tails.
Keep us posted on your progress. You have the hardest to find.
John
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66F100s Rule
In the cool still quiet of night you can hear chevies rusting away.
Keep us posted on your progress. You have the hardest to find.
John
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66F100s Rule
In the cool still quiet of night you can hear chevies rusting away.
Senior User
Joined: Jan 2001
Posts: 193
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From: Ohio
flickering headlights
Your switch has a circuit breaker in it,"it resets itself, this is done this way so you have lights til you can get safely stopped" since it new and good, you may have short in your hot wires going out to head lights,( your taillights & front marker lights should on a seperate fuse.) If you put some HI-OUTPUT bulbs or accessary lights running off your headlight circuit you may be overloading the amp limit therefore tripping the breaker.good luck "jeff"
Senior User
Joined: May 2001
Posts: 166
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flickering headlights
My dad had the same problem with his '76 f150.Ended up being the connections on the back of the alternator.They were corroded and loose.Cleaned and tightened and no more problems.Hope this helps.
Posting Guru
Joined: Jun 1999
Posts: 2,415
Likes: 3
From: Comox Valley, Canada
flickering headlights
Is it just the headlights flickering or all the lights?? If everything flickers it could be fluctuating voltage caused by alternator, regulator or wiring problems maybe even a loose alternator belt.
Check the voltage the next time they flicker. Even better if they will flicker when the truck is parked with hood open
If not hook a voltmeter to the headlight fuse, or cigarette lighter or some other 12 volt wire. Then drive the truck till they flicker and have someone watch the meter.
Varying voltage and it probably isnt a headlight problem. Then you can get the alternator and regulator checked out. Also check the connector at the regulator for corrosion and all the wires on the alternator as well. Dont forget to check the belt for tightness and shiny marks from slipping, plus all the ground wires.
Good luck.
Sparky
Check the voltage the next time they flicker. Even better if they will flicker when the truck is parked with hood open
If not hook a voltmeter to the headlight fuse, or cigarette lighter or some other 12 volt wire. Then drive the truck till they flicker and have someone watch the meter.Varying voltage and it probably isnt a headlight problem. Then you can get the alternator and regulator checked out. Also check the connector at the regulator for corrosion and all the wires on the alternator as well. Dont forget to check the belt for tightness and shiny marks from slipping, plus all the ground wires.
Good luck.
Sparky
Posting Guru
Joined: Jul 2001
Posts: 1,613
Likes: 2
From: Gainesville, FL
flickering headlights
I've got a 78 F150 that has flickering headlights. The headlights never go completely off, they just dim and then brighten. I replaced the voltage regulator and it solved the problem temporally. The alternator was bad which was damaging the regulator which caused the headlights to flicker.
Good Luck,Have Fun
KingFisher
Good Luck,Have Fun
KingFisher
Postmaster
Joined: Apr 2000
Posts: 2,838
Likes: 6
From: SD
flickering headlights
[font color=red size=2]I had the same problem with my '73 F100 about 3 years ago. After driving for a few miles, they would start to flicker. All the lights would click on and off together - head lights, dash lights, tail lights - total darkness, not fun... Mine ended up being a bare spot in the wiring to the tail lights. Between the rear bumper and the fuel tank (I have a rear tank) the wires go through a hole in a crossmember. They had rubbed through there and were shorting out to the frame. So I repaired the wires and put some rubber hose around them there. No problems since. So give your wires all a good look.
Marty
"Cleverly Disguised as a Responsible Adult"[/font]
Marty
"Cleverly Disguised as a Responsible Adult"[/font]
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New User
Joined: Dec 2020
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My experience with headlights
In regards to your flickering headlights in my experience with my trucks i have a 78 f250 had the same issue and tried all the same tactics. I found out the old ignition coil was shorting out internally. (A standard coil test) i replaced the ignition coil and it solved my problems.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Wow, that's a long shot fix. Glad it worked!
Thanks for adding it to the list of possibilities even though it's dug up from a 19 year old thread. Well worth it!
And welcome to FTE too Ryan.
Paul
Thanks for adding it to the list of possibilities even though it's dug up from a 19 year old thread. Well worth it!
And welcome to FTE too Ryan.
Paul
Laughing Gas
Joined: Mar 2016
Posts: 757
Likes: 43
From: Cheyenne, Wy
Hey Paul. At least Ryan knows how to use the search feature.
Lead Driver
Joined: Jul 2017
Posts: 9,606
Likes: 1,175
From: San Jose, CA
Yeah, I never really mind it when someone dredges up old business myself. Like you say, it shows that they not only know to search, but that they are willing to go way back and drag something out that is pertinent to their discussion.
I actually kind of like seeing threads that I missed the first time around because they were before my time here. First thing I thought of when I checked the dates (which I don't always do!) this time too.
Hope it keeps working out.
Paul
I actually kind of like seeing threads that I missed the first time around because they were before my time here. First thing I thought of when I checked the dates (which I don't always do!) this time too.
Hope it keeps working out.
Paul
Laughing Gas
Joined: Aug 2020
Posts: 821
Likes: 292
From: Pelham Alabama
Paul,
Yea I also forget to look at the dates on these threads. I just AssUme that someone is having a trouble and looking for a solution to a problem that someone might have had in the past.
One thing that would be nice with problems like this is if the OP would end the thread with WHAT WAS THE SOLUTION.
Many times people post issues like: Rough idle, miss firing, runs then shuts off, No spark and on and on.
Ill say it again,,,It would be real nice if they would come back complete the thread with what they found,,
Have a nice weekend.
Alex
Yea I also forget to look at the dates on these threads. I just AssUme that someone is having a trouble and looking for a solution to a problem that someone might have had in the past.
One thing that would be nice with problems like this is if the OP would end the thread with WHAT WAS THE SOLUTION.
Many times people post issues like: Rough idle, miss firing, runs then shuts off, No spark and on and on.
Ill say it again,,,It would be real nice if they would come back complete the thread with what they found,,
Have a nice weekend.
Alex