headlights flashing
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Senior User
Joined: Jul 2007
Posts: 276
Likes: 1
From: Lexington. Mi.
headlights flashing
hey fellas, I have a 74 250 4 by 4 with the 390and after a short while my headlight start flashing sometimes will stay on for a while sometimes they wont, anybody ever have this problem before
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
No headlight relay on these trucks. There's a circuit breaker built in to the headlight switch. Check for shorted, pinched wiring or frayed insulation downstream. An overcurrent condition is causing the breaker to interrupt.
Thread Starter
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Senior User
Joined: Jul 2007
Posts: 276
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From: Lexington. Mi.
are you talking about before or after the headlight switch
Cargo Master
Joined: Sep 2005
Posts: 2,954
Likes: 64
I've had problems with the OEM switches not being capable of handling Halogen bulbs. But I can't remember what year they started using halogens. In those cases we wired a relay for high and another for low beams and solved the problem. I'm guessing by now they are making the headlight switches to handle the amps, so if it is just a weak breaker in the head light switch a new switch should probably fix it. Unplug one of your headlights and see if they stay on twice as long, that will tell you the switch is weak.
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Senior User
Joined: Jul 2007
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From: Lexington. Mi.
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Thread Starter
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Senior User
Joined: Jul 2007
Posts: 276
Likes: 1
From: Lexington. Mi.
I've had problems with the OEM switches not being capable of handling Halogen bulbs. But I can't remember what year they started using halogens. In those cases we wired a relay for high and another for low beams and solved the problem. I'm guessing by now they are making the headlight switches to handle the amps, so if it is just a weak breaker in the head light switch a new switch should probably fix it. Unplug one of your headlights and see if they stay on twice as long, that will tell you the switch is weak.
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