PLEASE help!! Gauge lights not working.
5th Gear
Joined: Oct 2013
Posts: 5
Likes: 0
From: Calgary AB
Just went through this on my '78. If your dash is apart do a simple isolation test.
Test the dash cluster harness first. Connect a test light to the connector ground on the cluster and the positive lead for the dash lights and pull the light switch to the on position. If your test light does not light up you have a wiring or switch issue.
If your test light works on the previous test then do the following. Take your cluster and connect the dash light ground tab to the negative battery and the dash light positive to your battery positive post. You can connect various tabs and test all the lights. If you get dash lights your bulbs, connections and circuit board are fine. If any of the lights don't work the problem is in the cluster, most likely the printed circuit board. Even on visual inspection it's difficult to find the tiny cracks in the copper circuit. New circuit board under $100. If that fixes those lights it is most likely the same for your console circuit board.
Test the dash cluster harness first. Connect a test light to the connector ground on the cluster and the positive lead for the dash lights and pull the light switch to the on position. If your test light does not light up you have a wiring or switch issue.
If your test light works on the previous test then do the following. Take your cluster and connect the dash light ground tab to the negative battery and the dash light positive to your battery positive post. You can connect various tabs and test all the lights. If you get dash lights your bulbs, connections and circuit board are fine. If any of the lights don't work the problem is in the cluster, most likely the printed circuit board. Even on visual inspection it's difficult to find the tiny cracks in the copper circuit. New circuit board under $100. If that fixes those lights it is most likely the same for your console circuit board.
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
Update - new headlight switch - new dash harness - no change. No lights. The blinker makes a noise, but nothing is lighting up. Could I have gotten a bad headlight switch? Really thinking about ghetto rigging this thing....
Safety Car
Joined: Oct 2007
Posts: 3,729
Likes: 267
From: Austin Texas
Corvette of the Year Winner 2017
2016 C3 of Year Finalist
Leds work in 1 direction only. if you install the bulb backwards they will not work.
if you have the dash light switch dimmed, Leds will not work.
Dimmer must be full brightness, supplying full 12 volts if you use leds.
Corvettes always have poor dash light Gnds, each module must have good gnd.
(Module = Speed-o, Tach, center dash, console, wiper switch, and light switch !)
verify each gnd. wire, for each module.
the actual gnd point for all interior is high up inside the left side of dash,
this is your birdcage / Interior GND.
you also must ensure this common point is Gnded, to frame.
there should be a small braided gnd connection, on Exterior drivers side.
connecting frame to the birdcage.
if you have the dash light switch dimmed, Leds will not work.
Dimmer must be full brightness, supplying full 12 volts if you use leds.
Corvettes always have poor dash light Gnds, each module must have good gnd.
(Module = Speed-o, Tach, center dash, console, wiper switch, and light switch !)
verify each gnd. wire, for each module.
the actual gnd point for all interior is high up inside the left side of dash,
this is your birdcage / Interior GND.
you also must ensure this common point is Gnded, to frame.
there should be a small braided gnd connection, on Exterior drivers side.
connecting frame to the birdcage.
Thread Starter
Racer
Joined: May 2010
Posts: 448
Likes: 3
From: Olathe KS
Tonight I will turn a couple of the LED's around and see if that makes a difference. I sliced into 2 different gray wires (for the speedo lights) and applied manual 12V to both, and 1 of the lights that goes in the gauge cluster (like the oil pressure gauge) lights up. Same light no matter which I apply power to.
Can I wire all the grounds together and ground them to the same spot? Shouldn't matter right?
Can I wire all the grounds together and ground them to the same spot? Shouldn't matter right?
