headlights flicker on and off
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Joined: Oct 2016
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headlights flicker on and off
1984 f250
my headlights have started to flicker on and off for about 20 seconds at a time. all other lights are fine. only head lights. im thinking its the switch. i want your thoughts before i go ahead and replace the switch
my headlights have started to flicker on and off for about 20 seconds at a time. all other lights are fine. only head lights. im thinking its the switch. i want your thoughts before i go ahead and replace the switch
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
The switch has an internal circuit breaker. High resistance in the headlight wiring and harness, connections. If you clean up the circuit path the problem may go away.
If you want to see why, place a voltmeter probe on the negative battery terminal and the other on the negative terminal of the headlight bulb. Turn the headlights on. The voltage drop will be shown as a positive number. Anything more than a few tenths of a volt is excessive. This heats up the switch causing it to trip. Check the positive side too.
If you want to see why, place a voltmeter probe on the negative battery terminal and the other on the negative terminal of the headlight bulb. Turn the headlights on. The voltage drop will be shown as a positive number. Anything more than a few tenths of a volt is excessive. This heats up the switch causing it to trip. Check the positive side too.
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