Topic: all my guages stop working
in Forum: C3 Electrical
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Prairieville, LA - USA
Joined: 10/11/2004
Posts: 19
Vette(s): 1980 L-82 and 1993 Corvette Coupe
I just bought a 1980 vette. When I got it I expected some problems. When the headlights are turned on all of the guages stop working. I am not sure where to go or even how to start to find this problem, anyone have any ideas? 

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Hot Springs, AR - USA
Joined: 4/24/2004
Posts: 3236
Vette(s): 69 Conv #'s match 427, TKO-600/.64, 3.36HD-Posi, HT, T/T, PS, PB, PW, SP, Leather, Comp XE264HR & Roller Rockers & Lifters, Air-Gap RPM intake, Holley St Av 770 VS, MSD 6AL+Dist+Blaster SS, K&N, Jet-Hot Hooker Side-Pipes, Steeroids, Al Rad, Spal Fans
oops... thought you said gauge lights...
|UPDATED|10/13/2004 11:40:19 AM (AZT)|/UPDATED|
Easy one.
The ground to the gauges is not making contact. This usually happens where the harness connects to the printed circuit. But it could be anywhere in the ground circuit.
Why? With the lights off, the gauges find a ground by going backwards through the lights and makeing a ground path. When the lights are on, the ground is gone, and the gauges stop.
Try this just for fun. Run the car and use the head light knob to turn the dash lights brighter and dimmer. You can set the gauges where you want between actual reading and zero. The gauges will drop as the lights get brighter, and raise as the lights get dimmer.
Fix the ground and all will operate normally.
The ground to the gauges is not making contact. This usually happens where the harness connects to the printed circuit. But it could be anywhere in the ground circuit.
Why? With the lights off, the gauges find a ground by going backwards through the lights and makeing a ground path. When the lights are on, the ground is gone, and the gauges stop.
Try this just for fun. Run the car and use the head light knob to turn the dash lights brighter and dimmer. You can set the gauges where you want between actual reading and zero. The gauges will drop as the lights get brighter, and raise as the lights get dimmer.
Fix the ground and all will operate normally.
in Forum: C3 Electrical
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