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I have a volt gauge from a 80 trans am that I want to use in my 70 Chevy C10 pickup with LS engine. This would replace the old 'charge/discharge' gauge. I intend to use the choke 'window' of the gauge for a check engine indicator.
I need to know how to wire it. There are 3 threaded connector pins on the back. Two opposing pins have a 'resister bar' between them. A third pin is stand alone - I am guessing this is a ground/mounting pin.
From a online picture of the dash back of a trans am it would appear that when looking at the back of the gauge the 12v+ would go to the left terminal and the ground to the right terminal leaving the bottom terminal unused.
I have also seen pictures where 12v+ goes to left pin and a ground to the third pin leaving the right pin connected to the bar unused.
I am afraid to just try it - don't want to screw up gauge,
A voltage gauge requires only a very simple set of two connections. One wire goes to ground - very easy. The red (usually) wire goes to a 12 volt positive source that only supplies 12 volts when the ignition key is on. There are plenty of places to find this 12 volt positive source but your fuse panel likely has a connection for it called "IGN".
From: Jacksonville, FL (originally from Toronto Canada)
The third pin is probably for gauge illumination power (connected to the dash lighting). It can't hurt to test it as long as you use a jumper cable with a small amperage inline fuse in it just in case you short something. Use a 9 volt battery if you're really worried about it.
Guess I wasn't quite clear. I know I have to have ignition switched 12v+ and a ground.
The attached picture shows the back of the gauge with post labeled A,B,and C. You can also see window I hope to use as MIL.
I need to know what post to use as 12v+ and ground. I am afraid hooking it wrong will burn out or damage meter.
No pins are connected to the case. Resistances between posts are:
A to C - 127 ohmns
B to C = 254 ohmns
A to C - 127 ohmns
Sorry about focus
Last edited by lutronjim; Jun 6, 2020 at 08:31 PM.
From: Jacksonville, FL (originally from Toronto Canada)
If you use a 9-volt battery to test the connections to determine what they do, you will not damage the gauge even if you happen to reverse polarity while testing.
Alternatively, you could get a 1980 Chilton's manual and check the wiring schematic in there or you may be able to view the schematic online at Auto Zone - they have many wiring schematics available free if you create an account on their site.
Found info on 67-72chevytrucks.com forum.
The B post is not connected to anything but the resister bar and this is where switched power is connected. The voltage crosses the resister bar to A post which is connect to the meter coil. The other side of the meter coil is connected to the C post and this is where the ground is connected.
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Need help wiring voltage gauge 
