Headlights are out - The 1947 - Present Chevrolet & GMC Truck Message Board Network

duke10 · 08-29-2004, 01:10 AM

I have a 72 gmc short bed and the headlights don't go on. Taillights, dash lights and running lights are all okay. I am not real mechanical and was wondering if someone could give me the basics of troubleshooting this problem. By the way the high beams haven't worked since I purchased the truck 18 months ago. Thanks

tmcgrawlookalike · 08-29-2004, 01:17 AM

check your dimmer switch.replacement is about 5 dollars at a parts store.sorry,but i don`t recommend auto zone crap.hope this helps

bobs409 · 08-29-2004, 06:53 AM

I agree on the dimmer switch. To test, unplug the wiring harness from it and use a jumper wire. It should have 3 wires and one will have power. Jump that one to either of the other 2. If it's a bad switch or dirty connections, lights should work. Jump to the other terminal and again lights should work. One will be lows and the other will be highs.

Often times it's just dirty connections though.

duke10 · 08-29-2004, 06:57 PM

Thanks guys

**'68OrangeSunshine** · 08-30-2004, 02:54 AM

Be sure to also check the ground leads from the ends of the headlight harness to the radiator wall. One each left and right. The 4-eyed set-up is a little more prone to bad grounding than the 2 headlights of a Chevy. (I have a '71 Jimmy, too) Sand or file any corrosion from the terminal ends and around the screwhole and re-attach.

duke10 · 09-02-2004, 02:12 PM

great info, thanks

duke10 · 09-25-2004, 03:58 AM

You guys were right on, it was the dimmer switch. Thanks again guys. Regards, Scott

08-29-2004, 01:10 AM	#1
duke10 Active Member Join Date: Aug 2003 Location: san diego Posts: 833	Headlights are out I have a 72 gmc short bed and the headlights don't go on. Taillights, dash lights and running lights are all okay. I am not real mechanical and was wondering if someone could give me the basics of troubleshooting this problem. By the way the high beams haven't worked since I purchased the truck 18 months ago. Thanks

08-29-2004, 06:53 AM	#3
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	I agree on the dimmer switch. To test, unplug the wiring harness from it and use a jumper wire. It should have 3 wires and one will have power. Jump that one to either of the other 2. If it's a bad switch or dirty connections, lights should work. Jump to the other terminal and again lights should work. One will be lows and the other will be highs. Often times it's just dirty connections though. __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

08-30-2004, 02:54 AM	#5
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,448	Be sure to also check the ground leads from the ends of the headlight harness to the radiator wall. One each left and right. The 4-eyed set-up is a little more prone to bad grounding than the 2 headlights of a Chevy. (I have a '71 Jimmy, too) Sand or file any corrosion from the terminal ends and around the screwhole and re-attach. __________________ Every 25 years I like to rebuild that 292, whether it needs it or not.

08-29-2004, 01:17 AM	#2
tmcgrawlookalike Registered User Join Date: Jun 2004 Location: warr acres,oklahoma Posts: 650	check your dimmer switch.replacement is about 5 dollars at a parts store.sorry,but i don`t recommend auto zone crap.hope this helps

08-29-2004, 06:57 PM	#4
duke10 Active Member Join Date: Aug 2003 Location: san diego Posts: 833	Thanks guys

09-02-2004, 02:12 PM	#6
duke10 Active Member Join Date: Aug 2003 Location: san diego Posts: 833	great info, thanks

09-25-2004, 03:58 AM	#7
duke10 Active Member Join Date: Aug 2003 Location: san diego Posts: 833	You guys were right on, it was the dimmer switch. Thanks again guys. Regards, Scott



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