Electrical wiring problem (headlamps) - The 1947 - Present Chevrolet & GMC Truck Message Board Network

oldudeSS · 05-24-2002, 08:33 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!!!

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

71GMC_3/4T · 05-24-2002, 09:14 AM

The bright green wire is high beams and the brown wire is low beams. Sounds like you have is crossed up by they headlights. I don't know, maybe GMC is different than Chevy?
Just remove the bulb behind the indicator and use oncoming traffic as your indicator. "Flash-flash", "Oops, sorry!"
About half the cars on the road nowadays don't seem to have high-beam indicators in them. I think they left them off when they removed the turn signal lever...

05-24-2002, 08:33 AM	#1
oldudeSS Registered User Join Date: Apr 2001 Location: Whitney, Texas,America Posts: 28	Electrical wiring problem (headlamps) 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!!!

05-24-2002, 09:14 AM	#2
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	The bright green wire is high beams and the brown wire is low beams. Sounds like you have is crossed up by they headlights. I don't know, maybe GMC is different than Chevy? Just remove the bulb behind the indicator and use oncoming traffic as your indicator. "Flash-flash", "Oops, sorry!" About half the cars on the road nowadays don't seem to have high-beam indicators in them. I think they left them off when they removed the turn signal lever... __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.