No Backup Lights
Thread Starter
Intermediate
Joined: Apr 2013
Posts: 37
Likes: 0
No Backup Lights
The backup lights are my '72 LT1 Coupe are not working, and I need some help. I have power (12V) from the pink wire on the connector near the firewall. When I bypass the switch and connect power to the light green wire, I have no power in the rear backup light sockets (neither side).
Can someone help me troubleshoot the issue? Maybe a ground problem or wire issue from the fuse panel?
Thanks!
Can someone help me troubleshoot the issue? Maybe a ground problem or wire issue from the fuse panel?
Thanks!
Team Owner
Joined: Jul 2006
Posts: 22,153
Likes: 4,165
From: Kannapolis NC
If you're sure you are shorting 12v from the pink to the green at the firewall, and still get no backup lights, there are only a few options. A broken wire, or two bad bulbs, or two bad sockets. Run a jumper from the ground on the socket to the frame back there to eliminate a bad ground on the socket. Many times, the contact down in the socket gets corroded, or the bulb contact isn't making contact with the socket contact, or the base of the bulb isn't contacting the socket sides due to corrosion. Try putting pressure on the bulbs and see if they come on as you push.
If you have 12v on the pink, the fuse is good and you need to chase down the green wire from that firewall plug back toward the rear, but first eliminate the ground on the b/u sockets themselves and the bulb contacts. Verify that you have the correct single contact bulbs (1156, I think, but check the owner's manual). You can also eliminate the wire to the front by measuring for 12v on the single contact down in the socket. All it takes to light the bulb is 12v and a ground, so verify which is missing.
If you have 12v on the pink, the fuse is good and you need to chase down the green wire from that firewall plug back toward the rear, but first eliminate the ground on the b/u sockets themselves and the bulb contacts. Verify that you have the correct single contact bulbs (1156, I think, but check the owner's manual). You can also eliminate the wire to the front by measuring for 12v on the single contact down in the socket. All it takes to light the bulb is 12v and a ground, so verify which is missing.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Don't forget that you could also have a bad ground connection at the tail end of the car. A bad ground connection would produce exactly the same results as a missing power signal. A bulb will not light if the circuit is not fully completed.
Last edited by 7T1vette; Apr 19, 2016 at 07:59 AM.
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
The backup lights are my '72 LT1 Coupe are not working, and I need some help. I have power (12V) from the pink wire on the connector near the firewall. When I bypass the switch and connect power to the light green wire, I have no power in the rear backup light sockets (neither side).
Can someone help me troubleshoot the issue? Maybe a ground problem or wire issue from the fuse panel?
Thanks!
Can someone help me troubleshoot the issue? Maybe a ground problem or wire issue from the fuse panel?
Thanks!
Good luck... GUSTO
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
You can't check power getting to the socket without having a ground connection on your meter. It would be best to touch it to the bulb housing, so that the socket's ground path can be checked also. You can check continuity of the socket's grounding to the frame, to check out the circuit ground.
Last edited by 7T1vette; Apr 19, 2016 at 09:02 AM.
Thread Starter
Intermediate
Joined: Apr 2013
Posts: 37
Likes: 0
Thanks for the information - very helpful. I have a question about the light green wire that runs from the firewall through the dash wire cluster and then to the rear harness. I simply used a jumper wire to connect the pink wire and the light green wire and did see 12V coming from the light green wire at the firewall. The light green wire is difficult to trace under the dash but could I check for 12V coming off the connector from the dash cluster to the rear harness? Does the light green wire routing through any other connectors prior to the rear harness connector?
Thanks!
Thanks!
Le Mans Master
Joined: Sep 2003
Posts: 8,812
Likes: 2,029
From: eastern NC
Thanks for the information - very helpful. I have a question about the light green wire that runs from the firewall through the dash wire cluster and then to the rear harness. I simply used a jumper wire to connect the pink wire and the light green wire and did see 12V coming from the light green wire at the firewall. The light green wire is difficult to trace under the dash but could I check for 12V coming off the connector from the dash cluster to the rear harness? Does the light green wire routing through any other connectors prior to the rear harness connector?
Thanks!
Thanks!
https://www.corvetteforum.com/forums...-diagrams.html
Good luck... GUSTO
Team Owner
Joined: Jul 2006
Posts: 22,153
Likes: 4,165
From: Kannapolis NC
Click here for the 72 wiring diagram I got from Papawana
Corvette_1972_wiring.pdf
First, verify your ground at the rear, the sockets tie together and go to ground. The other bulbs at the rear use the same ground, so if they work it's either not the ground or both backup sockets aren't grounded. If you don't have 12v on the contact down in the socket with a GOOD ground on your meter, then you still have a problem with the lt green wire. You can always jump 12v to the light green wire at the back to eliminate the sockets and the grounds back there. You could also take a long piece of wire and connect it to the light green at the back and to the pink on the firewall. That would bypass everything in the middle, including the b/u switch
Corvette_1972_wiring.pdf
First, verify your ground at the rear, the sockets tie together and go to ground. The other bulbs at the rear use the same ground, so if they work it's either not the ground or both backup sockets aren't grounded. If you don't have 12v on the contact down in the socket with a GOOD ground on your meter, then you still have a problem with the lt green wire. You can always jump 12v to the light green wire at the back to eliminate the sockets and the grounds back there. You could also take a long piece of wire and connect it to the light green at the back and to the pink on the firewall. That would bypass everything in the middle, including the b/u switch
Last edited by 65GGvert; Apr 19, 2016 at 01:46 PM.
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