Back up and brake light help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

THOR 50 · 11-05-2005, 12:58 AM

Need a little info guys.
My '69 was originally a 3 on the tree. It was converted to an auto 400TH. It appears that the column is correct for a auto truck but I've got no back up lights. Has anyone done this swap and can give me some real world advice?
Do I need to install a fresh back up switch in the column or check the wiring?

Also I recently lost my passenger side brake light only. The bulb works for the turn signal, tail light works with head lights but no brake light on one side. The tail light harness is intact from the plug in the crossmember and I have a brand new correct bulb.

**truckdude239** · 11-05-2005, 02:00 AM

check the wireing from the plug back there an plug under the bottom of the truck toward the left fram rail on the bed that eveything plugs into i had to rewire all mine from there back

**pjmoreland** · 11-05-2005, 02:16 AM

You could test to see if the problem with your back up lights is with the switch by unplugging the connector from the switch and jump the two contacts on the connector together with a piece of wire. The connector has a light green wire and a dark green wire connected to it, and is located near the firewall, on the top of the steering column. If the lights turn on with the jumper in place, then your switch is either broken or not adjusted properly.

I'm guessing your turn signal switch assembly inside your column is worn out and causing your brake light not to work.

BowTieMan · 11-05-2005, 02:23 AM

When I had my shifter on the column my back up lights didn't work half the time, but if I wiggled the shifter they would kick on.

I also have an odd problem were when I turn my turn signal on I lose my brake lights.

Longhorn Man · 11-05-2005, 07:47 AM

Both of you need new turn signal switches.

THOR 50 · 11-09-2005, 12:31 AM

Purchased a new switch figuring it's nearly 40 years old must have failed but it appears I'm missing the harness to it. Does anyone know of a source to purchase one or help a schematic?
Guess it would be called the trans control harness?
Strange part is the original MT harness seems to be gone as well...

**pjmoreland** · 11-09-2005, 01:15 AM

What kind of switch did you buy? Did you by a turn signal switch, or did you buy a back up light switch?

Here's a link to wiring diagrams:

http://www.geocities.com/chevroletc1070/wiringdias.html

Here's the page that shows the back up switch. It's in the upper middle of the page:

http://www.geocities.com/chevroletc1070/instrum1.html

You should have a connector with one light green and one dark green wire running to it that should plug into the back up light switch. The dark green wire comes from the fuse panel, and the light green wire goes to the round connector next to the gas pedal that runs through the firewall, and back to the rear lighting harness.

THOR 50 · 11-10-2005, 12:57 AM

I appreciate the links! I baught a new back-up switch. Will try to post a pic so you can see why I'm having a hard time with this, thanks

THOR 50 · 11-14-2005, 10:13 PM

Looks like the 2 wires you referred me to are looped together. The old switch was a 4 prongs. The GP Sorenson replacement has 7 possible connections. Any help ?

**pjmoreland** · 11-15-2005, 02:56 AM

The switch should have four prongs on it. Two are for the back up lights and two are for the neutral safety connector, which doesn't allow you to start your truck if you aren't either in Neutral or Park. I don't think your truck will have the neutral safety connector though if you had a manual transmission. The purple wire that runs from your ignition switch to your starter motor is supposed to be routed through the neutral safety switch. It's not totally necessary, but is a good idea safety-wise.

Looks like you need to connect those green wires to the switch. The green wires need to connect to the two terminals that are not parallel and not really close to each other. If they are looped together, then I wonder if the previous owner installed a toggle switch on the dash or something for turning on the back up lights?

I bought a replacement Neutral Safety/back up light switch from Autozone about 6 months ago for $4.95.

11-05-2005, 12:58 AM	#1
THOR 50 Over worked under paid Join Date: May 2001 Location: Fort Myers, Florida Posts: 378	Back up and brake light help Need a little info guys. My '69 was originally a 3 on the tree. It was converted to an auto 400TH. It appears that the column is correct for a auto truck but I've got no back up lights. Has anyone done this swap and can give me some real world advice? Do I need to install a fresh back up switch in the column or check the wiring? Also I recently lost my passenger side brake light only. The bulb works for the turn signal, tail light works with head lights but no brake light on one side. The tail light harness is intact from the plug in the crossmember and I have a brand new correct bulb. __________________ Roger '69 C-10 with GMC front clip billet grill, 283CI, 400TH and 12bolt posiw/3.73 gears

11-05-2005, 02:00 AM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: Back up and brake light help check the wireing from the plug back there an plug under the bottom of the truck toward the left fram rail on the bed that eveything plugs into i had to rewire all mine from there back

11-05-2005, 02:16 AM	#3
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,426	Re: Back up and brake light help You could test to see if the problem with your back up lights is with the switch by unplugging the connector from the switch and jump the two contacts on the connector together with a piece of wire. The connector has a light green wire and a dark green wire connected to it, and is located near the firewall, on the top of the steering column. If the lights turn on with the jumper in place, then your switch is either broken or not adjusted properly. I'm guessing your turn signal switch assembly inside your column is worn out and causing your brake light not to work.

11-05-2005, 02:23 AM	#4
BowTieMan Registered User Join Date: Dec 2003 Location: Glendale Arizona Posts: 747	Re: Back up and brake light help When I had my shifter on the column my back up lights didn't work half the time, but if I wiggled the shifter they would kick on. I also have an odd problem were when I turn my turn signal on I lose my brake lights. __________________ "A true hotrodder wouldn't be content untill he had created a car so violent, so hairy, so totally sick that the very act of dropping the hammer would result in instant death. Anything less results in the need to go faster." - Tony DeFeo Last edited by BowTieMan; 11-05-2005 at 02:24 AM.

11-05-2005, 07:47 AM	#5
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Re: Back up and brake light help Both of you need new turn signal switches.

11-09-2005, 12:31 AM	#6
THOR 50 Over worked under paid Join Date: May 2001 Location: Fort Myers, Florida Posts: 378	Re: Back up and brake light help Purchased a new switch figuring it's nearly 40 years old must have failed but it appears I'm missing the harness to it. Does anyone know of a source to purchase one or help a schematic? Guess it would be called the trans control harness? Strange part is the original MT harness seems to be gone as well... __________________ Roger '69 C-10 with GMC front clip billet grill, 283CI, 400TH and 12bolt posiw/3.73 gears

11-09-2005, 01:15 AM	#7
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,426	Re: Back up and brake light help What kind of switch did you buy? Did you by a turn signal switch, or did you buy a back up light switch? Here's a link to wiring diagrams: http://www.geocities.com/chevroletc1070/wiringdias.html Here's the page that shows the back up switch. It's in the upper middle of the page: http://www.geocities.com/chevroletc1070/instrum1.html You should have a connector with one light green and one dark green wire running to it that should plug into the back up light switch. The dark green wire comes from the fuse panel, and the light green wire goes to the round connector next to the gas pedal that runs through the firewall, and back to the rear lighting harness.

11-10-2005, 12:57 AM	#8
THOR 50 Over worked under paid Join Date: May 2001 Location: Fort Myers, Florida Posts: 378	Re: Back up and brake light help I appreciate the links! I baught a new back-up switch. Will try to post a pic so you can see why I'm having a hard time with this, thanks __________________ Roger '69 C-10 with GMC front clip billet grill, 283CI, 400TH and 12bolt posiw/3.73 gears

11-14-2005, 10:13 PM	#9
THOR 50 Over worked under paid Join Date: May 2001 Location: Fort Myers, Florida Posts: 378	Re: Back up and brake light help Looks like the 2 wires you referred me to are looped together. The old switch was a 4 prongs. The GP Sorenson replacement has 7 possible connections. Any help ? Attached Images __________________ Roger '69 C-10 with GMC front clip billet grill, 283CI, 400TH and 12bolt posiw/3.73 gears

11-15-2005, 02:56 AM	#10
pjmoreland Senior Member Join Date: Jan 2005 Location: CA Posts: 5,426	Re: Back up and brake light help The switch should have four prongs on it. Two are for the back up lights and two are for the neutral safety connector, which doesn't allow you to start your truck if you aren't either in Neutral or Park. I don't think your truck will have the neutral safety connector though if you had a manual transmission. The purple wire that runs from your ignition switch to your starter motor is supposed to be routed through the neutral safety switch. It's not totally necessary, but is a good idea safety-wise. Looks like you need to connect those green wires to the switch. The green wires need to connect to the two terminals that are not parallel and not really close to each other. If they are looped together, then I wonder if the previous owner installed a toggle switch on the dash or something for turning on the back up lights? I bought a replacement Neutral Safety/back up light switch from Autozone about 6 months ago for $4.95.



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