Back up Lights - The 1947 - Present Chevrolet & GMC Truck Message Board Network

pinky350 · 04-03-2002, 07:55 PM

I have a 71 that use to be 6 cylinder with a 3 speed. For no reason the drivers side backup light comes on when I turn my head lights on.It just started this last week.
I replaced the wiring harness going to the back and side to side last year. All wires are in a wire loom. I just looked over the wires and find no bad spots rubs or anything.
When I press on the brakes the tail light goes out but backup light stays on.
I need some help guys.PLEASE

pinky350 · 04-03-2002, 08:37 PM

Ok took backup light bulb out of it's socket and it is working fine now. So what is the deal with the backup light?

RussTburb · 04-03-2002, 09:14 PM

I would check the grounds again and again! it alomast has to be a ground problem!

Kas68c10 · 04-10-2002, 02:16 PM

I had to take the light right off the pillar from the box of the truck,cleaned up where the peices come in contact,and I think I had to clean up something inside the light as well, to get it to ground properly. Had to be 6 years ago,been ok since

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1968 SWB Stepside, pwr disc brake and tilt pwr steering, 5 spd tranny, HEI,Accel coil,K&N filter,3 bolt seatbelts, original i6 and wood bed, seat from an 89 Chevy, front and rear sway bars, moved gas tank to under the bed, headman hedders, new chrome bumpers,one wire alternator,WORK IN PROGRESS,Daily driver, 20 MPG, Freeland MI

**COBALT** · 04-10-2002, 02:30 PM

Back up lights have their own local ground to the bedsides behind the housings. Same as the taillights. If he had no ground at all the lights wouldn't be on. He may be grounding to another source, but that wouldn't be affected by the headlights.

The rear harness (6 wires w/o side markers) runs to the first X member on the frame, and plug into a 4 wire harness that runs to the cab. In the cab they run to the firewall and to the fuse block where they run to the back-up switch.

You have to have some sort of short between the fuse block and the back-up switch somewhere. Did someone hack up the dash harness at all?

The reason I ask is you have to make sure a green and yellow are your lead and ground for the back-up lights. If anything else then you're getting power from another source, like your headlight circuit...

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'69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed!
'69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast).
Seattle, WA.

*See pics of my trucks and project at www.webshots.com!

[This message has been edited by new69owner (edited April 10, 2002).]

Reumster · 04-10-2002, 02:41 PM

While yuor in there throw some ultra bright bulbs in! They make a world of defference, exspecially with tinted windows! I did mine and love them. Hope Fully one day I have the money to upgrade the whole thing to LEDs.

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1972 2wd Blazer, 350/700R4/3:73 posi/NOS. Power is nothing without control!

04-03-2002, 07:55 PM	#1
pinky350 Registered User Join Date: Jun 2001 Location: TX Posts: 91	Back up Lights I have a 71 that use to be 6 cylinder with a 3 speed. For no reason the drivers side backup light comes on when I turn my head lights on.It just started this last week. I replaced the wiring harness going to the back and side to side last year. All wires are in a wire loom. I just looked over the wires and find no bad spots rubs or anything. When I press on the brakes the tail light goes out but backup light stays on. I need some help guys.PLEASE

04-03-2002, 09:14 PM	#3
RussTburb Registered User Join Date: Mar 2002 Location: Blaine,Wa. U.S.A Posts: 261	I would check the grounds again and again! it alomast has to be a ground problem! __________________ "Red-heads not war-heads, Blondes, not bombs, Brunettes, not fighter jets!" Fligh of the Choncords 72 burb 3/4 ton 2wd 06 2500 suburban 8.1L 4x4 84 chev 4x4 diesel 96 Geo Metro with the 4cylbb, lol! Almost 300k just won't die! 89 Honda Civic, runs on the smell of an oily rag! 2008 Aerolite 26qs Travel Trailer (aka "THE BARN")

04-10-2002, 02:16 PM	#4
Kas68c10 Registered User Join Date: Apr 2000 Location: Freeland,Michigan,USA Posts: 312	I had to take the light right off the pillar from the box of the truck,cleaned up where the peices come in contact,and I think I had to clean up something inside the light as well, to get it to ground properly. Had to be 6 years ago,been ok since ------------------ 1968 SWB Stepside, pwr disc brake and tilt pwr steering, 5 spd tranny, HEI,Accel coil,K&N filter,3 bolt seatbelts, original i6 and wood bed, seat from an 89 Chevy, front and rear sway bars, moved gas tank to under the bed, headman hedders, new chrome bumpers,one wire alternator,WORK IN PROGRESS,Daily driver, 20 MPG, Freeland MI __________________ 1968 SWB Stepside, 250,pwr disc brake and tilt pwr steering, 5 spd tranny, HEI,Accel coil,K&N filter,Seat from a later truck with built in seatbelts, front and rear sway bars, moved gas tank to under the bed, headman hedders, new chrome bumpers,one wire alternator,Weber k550cub carburator...WORK IN PROGRESS, Freeland MI , Just bought a 72 Jimmy!!!!!!!!!!!

04-10-2002, 02:30 PM	#5
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Back up lights have their own local ground to the bedsides behind the housings. Same as the taillights. If he had no ground at all the lights wouldn't be on. He may be grounding to another source, but that wouldn't be affected by the headlights. The rear harness (6 wires w/o side markers) runs to the first X member on the frame, and plug into a 4 wire harness that runs to the cab. In the cab they run to the firewall and to the fuse block where they run to the back-up switch. You have to have some sort of short between the fuse block and the back-up switch somewhere. Did someone hack up the dash harness at all? The reason I ask is you have to make sure a green and yellow are your lead and ground for the back-up lights. If anything else then you're getting power from another source, like your headlight circuit... ------------------ '69 3/4 ton C20 2wd w/ 350ci/400THM and a wood bed! '69 3/4 ton Custom 20 2wd w/ ORIGINAL 350ci/4sp Manual and a wood bed (parts beast). Seattle, WA. *See pics of my trucks and project at www.webshots.com! [This message has been edited by new69owner (edited April 10, 2002).] __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.

04-10-2002, 02:41 PM	#6
Reumster L.E.D. Freak Join Date: Jan 2002 Location: Polson MT Posts: 1,358	While yuor in there throw some ultra bright bulbs in! They make a world of defference, exspecially with tinted windows! I did mine and love them. Hope Fully one day I have the money to upgrade the whole thing to LEDs. ------------------ 1972 2wd Blazer, 350/700R4/3:73 posi/NOS. Power is nothing without control! __________________ Specializing in Custom L.E.D. inserts. http://www.ccled.com/ Contact me @ blazer2wd1972@hotmail.com (406)675-8082 or Joel @ jmcwaters@eps-corp.net 1972 2wd Blazer, 350/700R4/3:73 posi, err & Custom L.E.D. inserts! LOL

04-03-2002, 08:37 PM	#2
pinky350 Registered User Join Date: Jun 2001 Location: TX Posts: 91	Ok took backup light bulb out of it's socket and it is working fine now. So what is the deal with the backup light?



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