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Old 11-27-2011, 12:29 AM   #1
Jayphus
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High beam / Low beam light switch problems

I have a 1970 GMC and when I turn my lights on they work just fine but when I turn on the high beams and leave them on for 15 to 20 minutes all my lights will start blinking and then go out until I turn off the high beams. I have installed new lights and dimmer switch. "HELP"
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Old 11-27-2011, 01:07 AM   #2
chevykevy
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Re: High beam / Low beam light switch problems

Are the lights Halogen? I blew a regulator a couple yeas ago with halogen bulbs. Do you have an internal or external voltage regulator?
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Old 11-27-2011, 01:21 AM   #3
Jayphus
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Re: High beam / Low beam light switch problems

Yes, I do have Hogelon and I have a internal voltage regulator.
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Old 11-27-2011, 01:51 AM   #4
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Re: High beam / Low beam light switch problems

I had trouble with an external regulator. Not sure if the regulator is heating up? Lets hope someone others have some ideas as well.
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Old 11-27-2011, 10:58 AM   #5
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Re: High beam / Low beam light switch problems

the blinking is probably the circuit breaker in the headlight switch.
I would inspect all the wires from the dimmer switch to the headlights for damage, and if all looks OK then I'd replace the headlight switch.
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Old 11-27-2011, 12:51 PM   #6
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Re: High beam / Low beam light switch problems

Check the grounds on the core support too....
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Old 11-27-2011, 11:41 PM   #7
Longhorn Man
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Re: High beam / Low beam light switch problems

it'd be a good idea to chack and clean the grounds, but odds are 99% that it isn't the issue here.
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Old 11-28-2011, 03:01 AM   #8
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Re: High beam / Low beam light switch problems

Are the halogens powered off of relays or does the power to them go through the light switch?
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Old 11-28-2011, 10:05 AM   #9
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Re: High beam / Low beam light switch problems

On my 70 when I pull out on the light switch they come on and go back off. I can push the knob in a little and they come back on. I figure it's my switch. Play with yours and see if they go off and on.
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Old 11-28-2011, 11:51 PM   #10
Jayphus
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Re: High beam / Low beam light switch problems

The power to my lights go through the switch....But I have also changed it out to a new one as well.
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Old 11-29-2011, 12:51 AM   #11
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Re: High beam / Low beam light switch problems

Quote:
Originally Posted by Longhorn Man View Post
the blinking is probably the circuit breaker in the headlight switch.
I would inspect all the wires from the dimmer switch to the headlights for damage, and if all looks OK then I'd replace the headlight switch.
X2 I've seen this several times and it's usually the circuit breaker in the switch getting weak. A new switch should fix your problem.
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Old 11-29-2011, 01:15 AM   #12
murry11
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Re: High beam / Low beam light switch problems

You could have a rubbed marker light wire. I had that on a car and the head lamps would go out on high beam.
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Old 11-29-2011, 01:52 AM   #13
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Re: High beam / Low beam light switch problems

Here are two diagrams that show how to wire up relays for the lights. They will allow the high current for the headlights to bypass the headlight switch and the dimmer switch. It should prevent the headlight switch circuit breaker from tripping.

Name:  GMC%20Headlite%20Relay%20Diagram%201.jpg
Views: 3483
Size:  31.0 KB





Name:  HeadlightRelayWiringDiagram.jpg
Views: 2819
Size:  34.9 KB
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Old 11-29-2011, 09:47 AM   #14
Longhorn Man
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Re: High beam / Low beam light switch problems

Dont bother looking at the markers or tail lights... They have a fuse. The only things too look at is the headlight circuit.
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