Flickering tail lights - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Nima · 05-08-2004, 07:47 PM

Hey:
First of all thanks to whoever wrote me back about my carb problem. It is in rsolving process, I let you know as soon as I am done.
Now, at the same time I am working on the electrical system. My tail lights flicker and fade gradually when the engine running. Is it charging system and/or ground issue? My truck has messed up wiring, but at this point, I can't afford to buy wiring harnesses. I appreciate any input.
Thanks.
By the way, I am still working on posting pictures!

Jeepster376 · 05-08-2004, 07:51 PM

Bad ground at the rear frame.

Sweet72 · 05-08-2004, 11:05 PM

If all other lights are bright...Like Jeepster said check grounds and all connections, firewall feed-through, along LH frame rail and at last crossmember feed-through connector. Clean connections once you've found the problem and apply dielectric silicone grease inside connectors before re-assembly. Make sure all grounds are down to bare metal.

Jeepster376 · 05-08-2004, 11:19 PM

I say at rear of frame, because the tailight harness does not carry a ground wire. The rear lights ground to the frame after the rear crossmember pass through. Where it is exactly I'm not sure. If the lights flicker together, then that frame ground connection is most likely crusty.

Longhorn Man · 05-08-2004, 11:27 PM

The bad ground on the bed is even more likely if you have a wooden floor in the bed.

Hooter · 05-09-2004, 12:00 AM

Second what Andy said, after I put new wood in my bed I forgot to hook up the ground strap between the bed and the frame, and I was having all kinds of problems like one of my turn signal light would come on the dash and what not, sand down the metal between the two grounding points down tom bare metal, attach the strap then shoot the area you sanded down with paint to prevent the ground from rusting out

Nima · 05-09-2004, 06:04 PM

Thanks everybody. I am working on it although I have a hard time to rcognize ground wire since everything is the same color under the rear bumper and there is nothing connected to the frame!.

Jeepster376 · 05-09-2004, 08:23 PM

OK looking under my bed there are no ground wires this means the lights are grounded through the body which is bolted to the frame. Do you have a wood bed? Try like Hooter did and make a ground strap jumper wire connect one end to the body and the other end to the frame.

Nima · 05-09-2004, 08:47 PM

yes, I have wooden bed.

Longhorn Man · 05-09-2004, 10:40 PM

There is supposed to be a ground strap up towards the front of the bed if I'm not mistaken.
I normally just run a wire fron the tail light bucket through the inside of the bed (between the inner and outer sheet metal) and bolt it to the frame...never have ground issues.

05-08-2004, 07:47 PM	#1
Nima Blue 67 Join Date: Apr 2004 Location: Western WA Posts: 1,179	Flickering tail lights Hey: First of all thanks to whoever wrote me back about my carb problem. It is in rsolving process, I let you know as soon as I am done. Now, at the same time I am working on the electrical system. My tail lights flicker and fade gradually when the engine running. Is it charging system and/or ground issue? My truck has messed up wiring, but at this point, I can't afford to buy wiring harnesses. I appreciate any input. Thanks. By the way, I am still working on posting pictures!

05-08-2004, 07:51 PM	#2
Jeepster376 Registered User Join Date: Feb 2004 Location: Massachusetts Posts: 269	Bad ground at the rear frame. __________________ 72 Cheyenne Super 4x4 SWB

05-08-2004, 11:05 PM	#3
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	If all other lights are bright...Like Jeepster said check grounds and all connections, firewall feed-through, along LH frame rail and at last crossmember feed-through connector. Clean connections once you've found the problem and apply dielectric silicone grease inside connectors before re-assembly. Make sure all grounds are down to bare metal. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

05-08-2004, 11:19 PM	#4
Jeepster376 Registered User Join Date: Feb 2004 Location: Massachusetts Posts: 269	I say at rear of frame, because the tailight harness does not carry a ground wire. The rear lights ground to the frame after the rear crossmember pass through. Where it is exactly I'm not sure. If the lights flicker together, then that frame ground connection is most likely crusty. __________________ 72 Cheyenne Super 4x4 SWB

05-09-2004, 12:00 AM	#6
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,085	Second what Andy said, after I put new wood in my bed I forgot to hook up the ground strap between the bed and the frame, and I was having all kinds of problems like one of my turn signal light would come on the dash and what not, sand down the metal between the two grounding points down tom bare metal, attach the strap then shoot the area you sanded down with paint to prevent the ground from rusting out __________________ Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life

05-08-2004, 11:27 PM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	The bad ground on the bed is even more likely if you have a wooden floor in the bed.

05-09-2004, 06:04 PM	#7
Nima Blue 67 Join Date: Apr 2004 Location: Western WA Posts: 1,179	Thanks everybody. I am working on it although I have a hard time to rcognize ground wire since everything is the same color under the rear bumper and there is nothing connected to the frame!.

05-09-2004, 08:23 PM	#8
Jeepster376 Registered User Join Date: Feb 2004 Location: Massachusetts Posts: 269	OK looking under my bed there are no ground wires this means the lights are grounded through the body which is bolted to the frame. Do you have a wood bed? Try like Hooter did and make a ground strap jumper wire connect one end to the body and the other end to the frame. __________________ 72 Cheyenne Super 4x4 SWB

05-09-2004, 08:47 PM	#9
Nima Blue 67 Join Date: Apr 2004 Location: Western WA Posts: 1,179	yes, I have wooden bed.

05-09-2004, 10:40 PM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	There is supposed to be a ground strap up towards the front of the bed if I'm not mistaken. I normally just run a wire fron the tail light bucket through the inside of the bed (between the inner and outer sheet metal) and bolt it to the frame...never have ground issues.



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