Tail lights on a '72 GMC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JBMack · 06-04-2004, 11:34 PM

Can someone give me a hint to a problem I'm having with my tail lights. Everything works on them except the following scenario:

The left brake light doesn't work when the right signal is flashing. Do I need to purchase a new signal switch or what?

Please help.

*bisquik65* · 06-05-2004, 07:28 PM

First check for a good ground and check for trailer lite wires corroded . If these check ok then get a turn signal switch. I have a gm tester for turn signal switches. you plug it in and hit the switches and it tests all the ciruits .

camelot · 06-08-2004, 06:55 PM

Where can I get one of those testers. I have huge wiring problems.

*bisquik65* · 06-09-2004, 07:05 PM

I got mine from a friend that worked in the wilmington de gm plant that throws everything away each year. He worked there when they built my 65 biscayne. Thats why new cars cost so much. But take a new switch and just plug it in and try it without putting it in the coulmn. And get a wiring diag. what you said is what mine did also.

canarykid · 07-08-2004, 01:29 PM

I had the same problem. Check the trailer wireing like he said but it may save you a lot time and grief if you just replace the rear harness that goes to the turn signals. Mine turned out to be gronding out because the wires that run along the frame melted together from the exhaust.

LUV2XCLR8 · 07-09-2004, 03:53 PM

ANOTHER TN. MEMBER, COOL, CHECK THIS OUT

http://67-72chevytrucks.com/vboard/s....php3?t=109980

06-04-2004, 11:34 PM	#1
JBMack Registered User Join Date: Nov 2003 Location: Memphis TN Posts: 8	Tail lights on a '72 GMC Can someone give me a hint to a problem I'm having with my tail lights. Everything works on them except the following scenario: The left brake light doesn't work when the right signal is flashing. Do I need to purchase a new signal switch or what? Please help. __________________ JBMACk

06-08-2004, 06:55 PM	#3
camelot Registered User Join Date: Apr 2003 Location: Santa Clara, CA Posts: 39	Where can I get one of those testers. I have huge wiring problems. __________________ Camelot www.toyotagirl.com 1985 Chevy 4Runner 1972 GMC 4WD

07-08-2004, 01:29 PM	#5
canarykid Registered User Join Date: Jul 2004 Posts: 17	Wiring nightmare I had the same problem. Check the trailer wireing like he said but it may save you a lot time and grief if you just replace the rear harness that goes to the turn signals. Mine turned out to be gronding out because the wires that run along the frame melted together from the exhaust.

07-09-2004, 03:53 PM	#6
LUV2XCLR8 The LuvShack Garage Join Date: Jan 2004 Location: Maple Grove, TN (West Side) Posts: 30,468	ANOTHER TN. MEMBER, COOL, CHECK THIS OUT http://67-72chevytrucks.com/vboard/s....php3?t=109980 __________________ Owner/Op: "TN Classic Transport Carriers" The Toy: "Square Vette" 72 Hybrid Blazer Toy Barn: "LuvShack" 40 x 60 x 20 Shop Tow Piggy:"Maddy" 88 Silverado 3500 Hauler: "Feathers" 14 Aluma 8218T

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06-05-2004, 07:28 PM	#2
bisquik65 Account Suspended Join Date: Apr 2004 Location: N.C. high country Posts: 6,107	First check for a good ground and check for trailer lite wires corroded . If these check ok then get a turn signal switch. I have a gm tester for turn signal switches. you plug it in and hit the switches and it tests all the ciruits .

06-09-2004, 07:05 PM	#4
bisquik65 Account Suspended Join Date: Apr 2004 Location: N.C. high country Posts: 6,107	I got mine from a friend that worked in the wilmington de gm plant that throws everything away each year. He worked there when they built my 65 biscayne. Thats why new cars cost so much. But take a new switch and just plug it in and try it without putting it in the coulmn. And get a wiring diag. what you said is what mine did also.



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