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Intermittent Headlights

Ricks72Chlgr440

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72 Challenger. When the high beams are on, I will drive for about 10 minutes and the headlights will start flickering on and off. If I turn the high beams off, no problems. I replaced the dimmer switch but that did not fix it. When the headlights go off, the running lights stay on. Seems like maybe something is getting hot and causing an intermittent connection.

Any ideas?
 

Challenger RTA

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I would start by doing this. In general diagram.

headlight Harness schematic.jpg
 
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EW1BH27

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I had flickering headlights once, not with the high beams on either. Mine turned out to be the headlight switch. Problem went away when the switch was replaced with a used one I had kicking around.

I think I wrecked it by always flashing my headlights to let truckers know when they're clear to merge into my lane.
 

Chryco Psycho

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I would do the relay upgrade , it takes the load away from the headlight switch & the bulkhead connection which are the 2 weak points & the headlights will be brighter also .
 

72RoadRunnerGTX

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Circuit breaker in the headlight switch is failing. Replace the switch or do the relay mod. For a factory charging system, pull the relay secondary power from the alternator, not the battery as indicated above. Running an ammeter, all loads need to be on the alternator side of the ammeter.
Headlamp Mod.jpg
 

Steve340

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The headlight switch circuit breaker may in fact be working correctly and protecting as it should.
You may have a high resistance joint, a faulty light socket, damaged wire etc.
You need to check the current draw and all the connections before replacing the switch.
 

72RoadRunnerGTX

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Replacement headlamps drawing more than stock current without relays would also cause a correctly calibrated headlight switch circuit breaker to trip as described. High resistance in the headlight circuit would reduce current flow through the headlight switch, should not trip a good breaker. Agree, need to measure the current draw of the lights to determine a correct course of action.
 
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heminut

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I would do the relay upgrade , it takes the load away from the headlight switch & the bulkhead connection which are the 2 weak points & the headlights will be brighter also .
I agree, especially if you're running halogen headlamps. Those things draw a lot of current! I have LED headlamps, which draw hardly any current, and still did the relay conversion.
 

EW1BH27

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In case you weren’t aware member crackedback makes and sells a quality plug & play relay harness.
 

Ricks72Chlgr440

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In case you weren’t aware member crackedback makes and sells a quality plug & play relay harness.
Yeah, I got one from him for my Duster. Also got the wire that goes from the alt to the starter relay to bypass all the current going thru the firewall connector.
 
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