How do i track down light harness problem? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72gmcshorty · 05-10-2003, 08:26 PM

I think my headlight harness on my 72 gmc has a short somewhere. How do i track down this problem? I've grounded the crap out of this harness and still it won't work properly. As soon as I put power to the harness directly from battery, the yellow lights and the side turn signal lights come on. When I turn on my headlight switch, only one headlight comes on and the yellows and side markers stay on. When I put on the high beams, everything lights up. What could it be? My rad support is powder coated. HELP ME!!!

jef5150 · 05-10-2003, 10:23 PM

as simple as it sounds,,your low beam filament on your head light probably is burnt out?????take out the head that does work,and plug it in too the connector of the one that doesnt work,if it works replace the head light,the head lights are grounded through the harness,so you can just set it down in the engine compartment while you turn on the switch,,,,,,,,,always try the simplest things first,,,,,electrical problems are such a pain

Longhorn Man · 05-11-2003, 12:21 AM

By "turn signal lights come on", do you mean it is blinking?

72gmcshorty · 05-11-2003, 02:49 AM

I mean the side blinkers come on steady. Not blinking. I'm going to try to replace the light switch in the cab to see if that helps.

05-10-2003, 08:26 PM	#1
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	How do i track down light harness problem? I think my headlight harness on my 72 gmc has a short somewhere. How do i track down this problem? I've grounded the crap out of this harness and still it won't work properly. As soon as I put power to the harness directly from battery, the yellow lights and the side turn signal lights come on. When I turn on my headlight switch, only one headlight comes on and the yellows and side markers stay on. When I put on the high beams, everything lights up. What could it be? My rad support is powder coated. HELP ME!!! __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-11-2003, 02:49 AM	#4
72gmcshorty Registered User Join Date: Jul 2001 Location: North Delta, British Columbia Posts: 1,344	I mean the side blinkers come on steady. Not blinking. I'm going to try to replace the light switch in the cab to see if that helps. __________________ 1992 Gmc 2wd 1972 Chevy Blazer 2wd

05-10-2003, 10:23 PM	#2
jef5150 Inline 69 Join Date: Apr 2003 Location: valleysprings,california Posts: 1,018	as simple as it sounds,,your low beam filament on your head light probably is burnt out?????take out the head that does work,and plug it in too the connector of the one that doesnt work,if it works replace the head light,the head lights are grounded through the harness,so you can just set it down in the engine compartment while you turn on the switch,,,,,,,,,always try the simplest things first,,,,,electrical problems are such a pain

05-11-2003, 12:21 AM	#3
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	By "turn signal lights come on", do you mean it is blinking?



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