Voltmeter wiring

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ahshoe

Senior Member
Lost my direction from my guage trio wiring.Question how is a aftermarket voltmeter guage to a car with a generator?
 
Does the voltmeter have two terminals, not connected to the housing that holds the gauges or anything else?
If so...
and the vehicle is Negative ground, the Battery / Plus terminal of the voltmeter would connect to the Accessory terminal of the Ignition switch, and the Negative voltmeter terminal to a good Ground.

If the vehicle is Positive ground, the Negative terminal of the voltmeter would connect to the Accessory terminal of the Ignition switch, and the Plus terminal of the voltmeter connects to a good Ground.

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If you want the voltmeter inside the car (under the dashboard or somethin like that), I would trace down the big wire that connects from the starter solenoid and goes to the dashboard. Find out if it goes to a "Batt" terminal on the headlight switch first or goes to "Batt" terminal on ignition switch. Whichever one that wire land upon, double-lug that terminal for the power lead on your volt-meter, that way you will read actual full amount of battery voltage available at the battery.
The other lead off the voltmeter should be connected at a ground lug that is directly or indirectly connected to the battery or car frame. Make sure car battery has good clean ground connection to firewall and car frame.
If installing volt-meter under the hood, you can connect the voltmeter power lead to the first terminal the battery power cable lands on (likely the starter solenoid). May need to use a large ring-tongue terminal on your volt-meter power lead to connect to starter solenoid. Then run the ground wire down and connect to same lug on the engine or car frame that the battery ground is jumpered to. Mount volt-meter on isolated standoff bracket (insulated from metal fender apron or firewall).
 
You can connect a voltmeter to any electrical source. The accessory terminal of the starter switch is a good source. I would recommend a 12 gauge wire, but a 14 will do just as well. The gauge has to be grounded. I grounded mine to the dash.


I have put voltmeters in three cars that originally didn't have them, and that is how I did it.. Absolutely no problems


Assuming a 12 volt system - a 6 volt system may be different.


It isn't like installing a amp meter.
 
6 or 12 volt, I like the voltmeter on the run or accessory position on the key. That way its not a continuous draw, even if not much. Either way, if it's not on a fused wire, fuse the hot side as close as possible to the connection.

Checking the voltage at the battery and comparing it to other places is a good idea on old wiring. If you've got 6.6 or 13.7 volts (or whatever) running at the battery and much less than that at the ignition there's another connection that needs to be cleaned up.

All the 50's cars I've worked on had wiring where the insulation was starting to crack and fail, and many connections that were marginal. Look close when you're hooking it up.
 
ahshoe said:
Lost my direction from my guage trio wiring. ...
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Daves55Sedan said:
If you want the voltmeter inside the car (under the dashboard or somethin like that), I would trace down the big wire that connects from the starter solenoid and goes to the dashboard. Find out if it goes to a "Batt" terminal on the headlight switch first or goes to "Batt" terminal on ignition switch. Whichever one that wire land upon, double-lug that terminal for the power lead on your volt-meter, that way you will read actual full amount of battery voltage available at the battery.. . .
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miker98038 said:
6 or 12 volt, I like the voltmeter on the run or accessory position on the key. That way its not a continuous draw, even if not much. Either way, if it's not on a fused wire, fuse the hot side as close as possible to the connection. ...
Click to expand...
Yes, a fuse in the power wire to the voltmeter is highly recommended, and if the power wire for the meter is connected to one of the large "battery" wires, yes the meter will always be on, draining the battery when the car is parked.
 
Only when the key is in either the On or the Accessory position. (unless the switch is faulty)

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Can anybody tell me which color wire is the ACC. wire on the back of a 1961 Galaxie ignition switch? I have a molded rubber grommet of sort covering all the ignition switch terminals. There is threaded stud coming out the back that does not have any wires on it. Is this an ACC terminal or do I have to splice into another colored wire. If so what color wire? Also what size inline fuse should I use when tapping into this for my Voltmeter? Thanks so far for all the info.
 
ahshoe said:
Any idea on the fuse size on that hot + ,Voltmeter wire?
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Are there any panel lights on that three instrument cluster? Maybe on their own circuit?

The only load on that fuse will be the meter itself, so a really small fuse will do. 1/2 amp may be overkill?
 
paul2748 said:
You can connect a voltmeter to any electrical source.
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True, but if you connect the voltmeter at a terminal downstream of circuits feeding loads, the voltmeter will not measure the volt-loss of the sum total of those circuits.
That's why I tried to describe connecting the voltmeter power lead to the first electrically continuous power wire from the battery ahead of circuit taps feeding loads.
 
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