Headlights Going Crazy
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Junior User
Joined: May 2004
Posts: 88
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Headlights Going Crazy
I have a 1969 F250 and I have been having problems with my headlights. They will not stay on - When I turn them on they stay on for around 1-2 minutes and then they start flashing on and off randomely. I don't care much for wiring and don't want to start messing with it until I know what I should be looking for. Any ideas?
Lead Driver
Joined: Jan 2003
Posts: 9,893
Likes: 12
From: Ohio
Sounds like headlight switch. It gets hot, then loses contact. Been there.
Pretty typical if all original still.
If it is not the headlight switch, then try the bright switch on the floor. They have a tendency to get corroded and lose contact. When the lights starting blinking, kick the switch a few times and see if it makes a difference. Try switch LO to HI beams and see if it still blinks. If so, then it's the headlight switch. If it ceases, then it's the bright switch.
Pretty typical if all original still.
If it is not the headlight switch, then try the bright switch on the floor. They have a tendency to get corroded and lose contact. When the lights starting blinking, kick the switch a few times and see if it makes a difference. Try switch LO to HI beams and see if it still blinks. If so, then it's the headlight switch. If it ceases, then it's the bright switch.
Fleet Mechanic
Joined: Aug 2001
Posts: 1,526
Likes: 0
From: Round Rock, TX
Ditto on the switch. Mine started doing this on a rural highway at about 1 AM right after somebody passed me. I think I scared the hell out of him as we were the only two vehicles in sight for miles.
New User
Joined: Jun 2004
Posts: 6
Likes: 0
Check the rest of your light like your interior light, if it starts diming high then low it can be your alternator,battery or your engine cold be ideling to low.
When mine was doing that it was because the engine was ideling to low and was not turning the alternator enough, also make sure your belts is not loose to your alternator or its not worn or cracked.
When mine was doing that it was because the engine was ideling to low and was not turning the alternator enough, also make sure your belts is not loose to your alternator or its not worn or cracked.
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Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
You can check the dimmer switch by removing the switch and using a jumper wire. Make sure you use the low beams. 
If they no longer blink, change the dimmer switch. If they still "blink" Change the Headlamp switch. There is a circut breaker in the headlight switch. When the switch gets old, the breaker which is a heat sensitive spring type, gets weak and breaks the circut.
It flashes on and off because it keeps cooling off and re-heating.
If you replace the headlamp switch and it still does it, check your wiring cause there may be a short.
If they no longer blink, change the dimmer switch. If they still "blink" Change the Headlamp switch. There is a circut breaker in the headlight switch. When the switch gets old, the breaker which is a heat sensitive spring type, gets weak and breaks the circut. It flashes on and off because it keeps cooling off and re-heating.
If you replace the headlamp switch and it still does it, check your wiring cause there may be a short.
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Senior User
Joined: Nov 2000
Posts: 366
Likes: 0
From: Calgary
I have exactly the same problem. For me, it's running to much current through a common ground. Atleast, that's what I think the problem is. Everytime I hook up the lights for my autometer guages, my headlights start flashing.
I still have to try another ground to see if it's the problem.
I still have to try another ground to see if it's the problem.
Senior User
Joined: Sep 2003
Posts: 184
Likes: 0
Guys,
This problem might be associated with adding new headlights that use more current than the originals. This, in turn, causes the circuit breaker to cycle--just like it's supposed to. This causes the on and off phenomenon of the lights. The answer is to add relays. There are numerous posts about this and (Ken, help me out here) a Technical Instruction somewhere.
This problem might be associated with adding new headlights that use more current than the originals. This, in turn, causes the circuit breaker to cycle--just like it's supposed to. This causes the on and off phenomenon of the lights. The answer is to add relays. There are numerous posts about this and (Ken, help me out here) a Technical Instruction somewhere.
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
Well, I guess i'll add my 2 cents. My troubles, was a dirty connection plug under the hood where the cab-wiring connects to the fender wiring for the head lights. Cleaned and a shot of WD-40 or dielectric grease. Also that circuit breaker inside cab next to the glove box on some models..
orich
orich
New User
Joined: Jan 2008
Posts: 0
Likes: 24
Go here .
https://www.ford-trucks.com/articles/index.html
& look for the "Whiter Whites Brighter Brights" tech article
https://www.ford-trucks.com/articles/index.html
& look for the "Whiter Whites Brighter Brights" tech article
Senior User
Joined: Nov 2000
Posts: 366
Likes: 0
From: Calgary
Originally Posted by Mil1ion
Go here .
https://www.ford-trucks.com/articles/index.html
& look for the "Whiter Whites Brighter Brights" tech article
https://www.ford-trucks.com/articles/index.html
& look for the "Whiter Whites Brighter Brights" tech article
God I hate wiring.
Freshman User
Joined: Apr 2004
Posts: 40
Likes: 0
Replacing Headlight Switch
Hello , my headlights started flashing eratically last night . I assume its the switch as they flash with both the low beams and high beams . Can someone tell me the procedure for changing the headlight switch ? I get a little cautious when it comes to electrical items. Thank you very much. 
Lead Driver
Joined: Aug 2003
Posts: 7,592
Likes: 10
From: **** hole San Jose ca.
That does not sound like the dash light switch to me. Sound more like your light relay is doing when it's over loaded or it's bad. Most 69thr70 I've seen there up next to the glove box under the dash....my 2 cents
orich
orich