PLEASE help!! Gauge lights not working.
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
PLEASE help!! Gauge lights not working.
I have my interior out - to replace the gauge lights with LEDs, replace my headlight switch, and install an electric tach.
Tested the tach - it works.
Test the lights before I put everything back together, and no lights (EXCEPT the turn signals, "BRIGHTS", and "BRAKE". None of the center gauge lights, or speedo/tach lights come on. Used my voltmeter on the light switch coil and ground, and it's running 12v. Checked the fuses - they're good.
This was the main reason I took all this stuff out! Please help, let me know what to do. I still have the interior out to troubleshoot. I don't want the answer to be "buy a $500 dash harness".
Thanks everyone.
Tested the tach - it works.
Test the lights before I put everything back together, and no lights (EXCEPT the turn signals, "BRIGHTS", and "BRAKE". None of the center gauge lights, or speedo/tach lights come on. Used my voltmeter on the light switch coil and ground, and it's running 12v. Checked the fuses - they're good.
This was the main reason I took all this stuff out! Please help, let me know what to do. I still have the interior out to troubleshoot. I don't want the answer to be "buy a $500 dash harness".
Thanks everyone.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Ground to the speedo/tach has nothing to do with the center gauge cluster. It has a separate ground via the trans tunnel route. Use a piece of 'dummy' wire to link a known-good grounding point to the chrome surface [edging] on the gauge cluster and turn on the light switch. If the gauge lights come on, there's your problem.
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
You checked the instrument fuse, yes?
The ground for the "center gauge cluster" starts at the center terminal of the water temp gauge and connects to the bird cage just above the bottom of the dash.
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Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
Just making sure it's those two. I am going to connect all 3 to 1, and set it to the kick panel. I'll keep you guys updated. Thanks! Just wanted to make sure those two were the wires I needed. They don't need to ground to the actual housings right? Just to the harness?
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
http://www.vetteprojects.com/bmv/mis...tte%201973.pdf
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
On this schematic the speedometer, the tachometer, the center gauge cluster and the black wire from the water temperature gauge are the same wire.
http://www.vetteprojects.com/bmv/mis...tte%201973.pdf
http://www.vetteprojects.com/bmv/mis...tte%201973.pdf
Racer
Joined: Jan 2013
Posts: 326
Likes: 7
- Have you manually supplied ground to verify it IS a ground issue?
- Do you have the headlight knock rotated so that all lights are turned on?
- Manually supply 12v through the headlight wiring harness to rule out a switch issue
- Manually supply 12v and ground to various lights to rule out both 12v and ground issues
I just got through doing all this myself actually, and it turned out to be a combination of several of the above issues
- Do you have the headlight knock rotated so that all lights are turned on?
- Manually supply 12v through the headlight wiring harness to rule out a switch issue
- Manually supply 12v and ground to various lights to rule out both 12v and ground issues
I just got through doing all this myself actually, and it turned out to be a combination of several of the above issues
Le Mans Master
Joined: Aug 2006
Posts: 7,427
Likes: 1,560
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
A few easy things to check
The "Tail light" fuse feeds the headlight rheostat so make sure it's good and that the K N O B is full CCW or the K N O B is pulled out.
If the lights are still out jumper from the "courtesy light" fuse to the "instrument light" fuse.
If the bulbs light then the rheostat in your new switch is bad.
If the lights are still out jumper from the "courtesy light" fuse to the "instrument light" fuse.
If the bulbs light then the rheostat in your new switch is bad.
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
I don't understand how to read the wiring schematic.. The part of the harness that connects to the headlight switch has been burnt to some degree.. The plastic is black and brown on part of it, where the two connect, instead of whitish. I tried manually supplying a ground and no luck. **** is pulled and turned the correct way. So frustrated right now. Tested the burnt part of the connection and it is still running 12.5v. My headlights etc are all coming on still, just not my gauge lights.
Racer
Joined: Jul 2006
Posts: 478
Likes: 56
From: Woodstock Georgia
I just went through all of this on my `75. Since NONE of them are working, double check the ground that goes to the instrument cluster. Notice that all of the gray wires only have one wire. The ground comes from the ground supplied to the instrument cluster to complete the circuit. If the ground is good, check the voltage to the gray wires that feed the lamp sockets. If you have no voltage, then either you have a blown fuse, 12V not switching through headlight switch or the headlight switch's rheostat is not turned far enough counter-clockwise.
Burning Brakes
Joined: Jul 2006
Posts: 1,047
Likes: 12
From: SoCal
BDoc has it right, follow his advice. Since you say you have definitely supplied a good ground, try manually supplying 12V to them and make sure the lights come on. Then use a voltmeter on the headlight switch's 12V feed to the gauge lights and see if there's any output - I bet there isn't.
Last edited by VCuomo; Sep 28, 2013 at 09:22 PM.
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
How do I supply ground and power to an individual light? They only have the one wire. The ground wire in the harness comes out (I believe) 3 times. I have attached one to a known ground. That should solve that right? Where can I get the 12v power from?