C'mon guys...I really need a hand!! (Electrical) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

oldudeSS · 05-25-2002, 07:17 AM

When I built my 72 GMC "Blaster" I used parts from any place I could get them...at any rate, when I got to the part of electrical, I found that my headlamps (high and low beam)
were reversed. eg: when the red lamp indicater is on on the dash only two of the four lamps would light up and when hitting the dimmer switch, the indicater will go out and all four lamps will burn. I replaced the dimmer "foot switch" but no change...
The only thing I can think of is that the wiring harness I used is from a Chevy, which means it's only wired for dual headlamps vs quads on a GMC....Has anyone had this prob??
HELP!!!

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1972 GMC Jimmy (topless reigns)
1996 ImpalaSS
1994 ImpalaSS
too many toys!!!

RALLY FAST · 05-25-2002, 12:11 PM

i think gmc has 2 leds for head lights ,chevy has 1. in harness under the dash. where the fuse box is , pluggs in on the fire wall. unplug it,check your harness that the lights run too,should be the right one, look at the metal leds and see if they match to the harness on the fire wall, if not that could be your problem. that means you have a chevy headlight harness on a gmc fuse panel. you will need a gmc headlight harness

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69 SHORT FLEET SIDE MAROON RESTORED.
71 LONG FLEET RESTORED D/DRIVER. BUT ALWAYS LOOKING TO IMPROVE 68 SHORT UNDER CONSTRUCTION

TERRYP · 05-25-2002, 08:57 PM

What's the problem? You have a truck with a 'low beam indicator light'. if you want a truck with a 'hi beam indicator light', simply connnect the lt green wire that goes to your dash to the headlight wire that is hot when all 4 lights are on, instead of to the other wire (that is tan)

**1970 CST Short Wide** · 05-25-2002, 09:09 PM

I had the same problem after putting in a new circuit board in my dash cluster. After pulling out most of my hair I found that there are 2 of the screw on the circuit board that are grounds and 1 was not making contact, tighted it up and all was good. Took me the cest part of 2 weeks to figure this out.

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Steve's 70 CST
02 Burb (wifes Truck)
www.picturetrail.com/70CST
Pittsburg Ca., that's right Ca.

05-25-2002, 07:17 AM	#1
oldudeSS Registered User Join Date: Apr 2001 Location: Whitney, Texas,America Posts: 28	C'mon guys...I really need a hand!! (Electrical) When I built my 72 GMC "Blaster" I used parts from any place I could get them...at any rate, when I got to the part of electrical, I found that my headlamps (high and low beam) were reversed. eg: when the red lamp indicater is on on the dash only two of the four lamps would light up and when hitting the dimmer switch, the indicater will go out and all four lamps will burn. I replaced the dimmer "foot switch" but no change... The only thing I can think of is that the wiring harness I used is from a Chevy, which means it's only wired for dual headlamps vs quads on a GMC....Has anyone had this prob?? HELP!!! ------------------ 1972 GMC Jimmy (topless reigns) 1996 ImpalaSS 1994 ImpalaSS too many toys!!! __________________ 1972 GMC Jimmy (topless reigns) 1996 ImpalaSS 1994 ImpalaSS too many toys!!!

05-25-2002, 12:11 PM	#2
RALLY FAST Registered User Join Date: Apr 2002 Location: knox, Tenn. Posts: 150	i think gmc has 2 leds for head lights ,chevy has 1. in harness under the dash. where the fuse box is , pluggs in on the fire wall. unplug it,check your harness that the lights run too,should be the right one, look at the metal leds and see if they match to the harness on the fire wall, if not that could be your problem. that means you have a chevy headlight harness on a gmc fuse panel. you will need a gmc headlight harness ------------------ 69 SHORT FLEET SIDE MAROON RESTORED. 71 LONG FLEET RESTORED D/DRIVER. BUT ALWAYS LOOKING TO IMPROVE 68 SHORT UNDER CONSTRUCTION __________________ 69 SHORT FLEET SIDE MAROON RESTORED. 71 LONG FLEET RESTORED D/DRIVER. BUT ALWAYS LOOKING TO IMPROVE 68 SHORT UNDER CONSTRUCTION

05-25-2002, 08:57 PM	#3
TERRYP GYRO GEARLOOSE Join Date: Jun 2000 Location: Nevada City, CAEverett, WA Posts: 361	What's the problem? You have a truck with a 'low beam indicator light'. if you want a truck with a 'hi beam indicator light', simply connnect the lt green wire that goes to your dash to the headlight wire that is hot when all 4 lights are on, instead of to the other wire (that is tan) __________________ Nevada City, CA Everett, Washington 57 3/4 rat, 235, 3spd 66 C-10 Panel, SWB. 350 from '68, 200R4 tranny, 3.07 rear ratio, restoring 68 C10 LWB 350 4spd, 4.56 rear dump runner 82 Camaro, 305, THM-200-R4 84 Monte Carlo 305 TH350, land tuna 85 Tercel SW, snow runner DISGRACED OUTLAW MEMBER OF THE DRUM BRAKE CLUB

05-25-2002, 09:09 PM	#4
1970 CST Short Wide Senior Moment Join Date: Mar 2002 Location: Pittsburg Ca Posts: 4,185	I had the same problem after putting in a new circuit board in my dash cluster. After pulling out most of my hair I found that there are 2 of the screw on the circuit board that are grounds and 1 was not making contact, tighted it up and all was good. Took me the cest part of 2 weeks to figure this out. ------------------ Steve's 70 CST 02 Burb (wifes Truck) www.picturetrail.com/70CST Pittsburg Ca., that's right Ca. __________________ 1970 CST LS 1 6 speed Ford 9 inch Detroit Tru Track, Dakota Didgital, Vintage Air, QA1 Coil Overs Front & Rear Lots of FUN 2013 GMC PU, Oldest Son 71 GMC LWB. QA1 Suspension, Angry SB. Youngest Son 2019 GMC Diesil Dually. Youngest Son 2017 Toyota SUV Daughters car 2018 Traverse , Wife’s Ride Pittsburg Ca 94565

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