dimmer switch - The 1947 - Present Chevrolet & GMC Truck Message Board Network

tttuba · 07-07-2011, 02:03 AM

OK please help again. I replaced my wire harness in cab and under hood etc. Got everything working and actually had headlamps working correctly. Then another time when I turned on headlamps...nothing. Hit dimmer switch and either the highs or the lows came on but not sure. When I hot the switch again...no lights. I thought the switch went out so I ordered a new one. Same thing happens. When I test it with a meter, I get power to one pole and then hit switch and power to the other pole but not the two together. Yet still only get lights on one click of the dimmer switch. Any ideas? Is switch bad? Should both poles get power on one of the clicks of the switch?

**mr48chev** · 07-07-2011, 11:15 AM

I think you have your hot wire going to to one of the poles that should be either going to high or low beam.

The hot wire from the headlight switch usually goes to the pole on the switch that is top center and the high and low beams hook to the two that are parallel with each other. right now you have the hot lead hooked to one of the headlight poles and one side of the headlights hooked to the pole that the hot lead should be on.

**mr48chev** · 07-07-2011, 12:00 PM

Can't edit the blasted post after 30 minutes so here is a diagram that shows how the dimmer switch is usually hooked up. This is for a Jeep wagon but it shows where the wires go and works if you use a bit of imagination.
note that it shows the hot wire going to the pole as I described above.

99 to Life · 07-08-2011, 11:03 AM

did your wiring harness have the dimmer wires connected to a 3 way plug or did you have to wire them to your dimmer personally? If you did personally I'd say you might have something backwards. If not, I'd say check the grounds
really good.

I have had my lights go in and out a couple times, and when I push my switch off and on it fixes it. I haven't checked my grounds since cause it was a random situation, but I'll check them to be sure.

My wiring harness has a high beam indicator wire, I wired that to my original gauge which has a red light to indicate if you are on high or low.

OrrieG · 07-08-2011, 01:03 PM

Here is what the factory wiring diagram shows. Most aftermarket harnesss have a three wire plug for the dimmer.

tttuba · 07-09-2011, 03:45 PM

Thanks everyone for the help. I found out it was actually the fuse block on the firewall. After a lot of probing with my meter I found the power wasn't getting from the wire to the fuse holder. Was a loose connection at the fuse holder. It is working now. I ordered another fuse holder panel to make sure it doesn't happen again. Just a really strange problem. Hey it is 64 years old. Hope I still work as well at 64.

07-07-2011, 02:03 AM	#1
tttuba Registered User Join Date: Oct 2010 Location: Olympia WA Posts: 180	dimmer switch OK please help again. I replaced my wire harness in cab and under hood etc. Got everything working and actually had headlamps working correctly. Then another time when I turned on headlamps...nothing. Hit dimmer switch and either the highs or the lows came on but not sure. When I hot the switch again...no lights. I thought the switch went out so I ordered a new one. Same thing happens. When I test it with a meter, I get power to one pole and then hit switch and power to the other pole but not the two together. Yet still only get lights on one click of the dimmer switch. Any ideas? Is switch bad? Should both poles get power on one of the clicks of the switch?

07-07-2011, 11:15 AM	#2
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,718	Re: dimmer switch I think you have your hot wire going to to one of the poles that should be either going to high or low beam. The hot wire from the headlight switch usually goes to the pole on the switch that is top center and the high and low beams hook to the two that are parallel with each other. right now you have the hot lead hooked to one of the headlight poles and one side of the headlights hooked to the pole that the hot lead should be on.

07-07-2011, 12:00 PM	#3
mr48chev Registered User Join Date: Jul 2007 Location: Toppenish, WA Posts: 15,718	Re: dimmer switch Can't edit the blasted post after 30 minutes so here is a diagram that shows how the dimmer switch is usually hooked up. This is for a Jeep wagon but it shows where the wires go and works if you use a bit of imagination. note that it shows the hot wire going to the pole as I described above.

07-08-2011, 11:03 AM	#4
99 to Life Registered User Join Date: Jan 2010 Location: Titusville, PA Posts: 3,585	Re: dimmer switch did your wiring harness have the dimmer wires connected to a 3 way plug or did you have to wire them to your dimmer personally? If you did personally I'd say you might have something backwards. If not, I'd say check the grounds really good. I have had my lights go in and out a couple times, and when I push my switch off and on it fixes it. I haven't checked my grounds since cause it was a random situation, but I'll check them to be sure. My wiring harness has a high beam indicator wire, I wired that to my original gauge which has a red light to indicate if you are on high or low. __________________ 51' 99toLife finished 2011,355 sbc,5speed, patina, redoing whole truck, inter, bags, etc http://67-72chevytrucks.com/vboard/s...d.php?t=382481 49Hardtimes s/10 susp- bagged, vortec sbc, 5 speed, patina, sold http://67-72chevytrucks.com/vboard/s...d.php?t=594874 VIDEOS https://youtu.be/E8zHhjgS_lA https://youtu.be/E8zHhjgS_lA Geronimo 54' LS engine, static drop IFS, Client build, just about done http://67-72chevytrucks.com/vboard/s...62#post7399162 52' 3100 Slowly in progress, will be painted two toned, have 235 with a t-5, lowered OG frame Other projects, 49' farmuse 3100, killer Patina, will be slammed, LS engine, full done interior up next! www.coffeeandcustoms.com

07-09-2011, 03:45 PM	#6
tttuba Registered User Join Date: Oct 2010 Location: Olympia WA Posts: 180	Re: dimmer switch Thanks everyone for the help. I found out it was actually the fuse block on the firewall. After a lot of probing with my meter I found the power wasn't getting from the wire to the fuse holder. Was a loose connection at the fuse holder. It is working now. I ordered another fuse holder panel to make sure it doesn't happen again. Just a really strange problem. Hey it is 64 years old. Hope I still work as well at 64.



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