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Old 11-22-2014, 07:12 PM   #1
Lerch1145
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Low beams

Good evening, first question with my 1972 GMC C25:

Headlights only work with high beam switch pushed. I have checked all bulbs and replaced one inboard bad bulb, inspected fuses under dash with no issues, replaced floor dimmer switch with neg results.
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Old 11-22-2014, 07:41 PM   #2
mrein3
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Re: Low beams

Sounds likes a furry dimmer switch plug. Unplug your new dimmer and spray the plug with contact cleaner.
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Old 11-26-2014, 10:27 PM   #3
Lerch1145
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Talking Re: Low beams

Thanks mrein3! That did it but it sent me down a road of spraying all electrical connectors.
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Old 11-27-2014, 11:27 AM   #4
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Re: Low beams

Sorry about that.

FWIW, I keep a can of radio shack electrical contact cleaner on hand. I also stock new brass colored inserts for all those connectors. Most of them are the female side but I stock both male and female. Jump over to NAPA and google these two parts: 725147 and 725145. These are the NAPA part numbers for the "Packard Type 56" connectors used just about everywhere on our trucks.

With a handful of the packard connectors and the spray, there is no excuse for anything electrical not to work on our trucks.

But be careful. The next thing you know you will find yourself down at the hardware store buying new wire to replace all the 40 year old brittle, cracked wire on your truck.
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Old 11-27-2014, 12:49 PM   #5
michael bustamante
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Re: Low beams

Switch might be going out too
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Old 11-27-2014, 02:41 PM   #6
VetteVet
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Re: Low beams

Do yourself a real big favor and wire in the headlight relay kit or make your own if you have the wiring and 2 Bosch relays. This will give you more voltage to your headlights and will take the load off your headlight and dimmer switches.

It's easy to wire up. Just follow the diagrams below. They are both the same wiring setup.

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I like the top one because it uses two power supply wires so one set of lights will work if the fuse blows on the other set








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Old 11-27-2014, 10:21 PM   #7
Lerch1145
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Re: Low beams

Do you have a parts list or pictures on a example install? Saw the pre-made harness but $100 is extream.
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Old 11-28-2014, 02:33 AM   #8
VetteVet
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Re: Low beams

Here's a good thread.
Check the link in post three, read post four and look at the pictures in the rest of the thread. The junkyard is full of cars with these relays and you can buy new ones at any auto parts store.
http://67-72chevytrucks.com/vboard/s...d.php?t=293913
.........
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Old 11-28-2014, 04:50 AM   #9
Warrens69GMC
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Re: Low beams

36-3581 = 29.99+shipping

http://www.lmctruck.com/icatalog/cb/full.aspx?Page=76
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Old 11-28-2014, 10:51 PM   #10
Lerch1145
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Re: Low beams

Awesome! Saved me time and money, ordered.
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