How to Wire a Voltmeter | DoItYourself Author: Ryan Dennis Determine Voltmeter Location. Your voltmeter should be located in a place where you can see it Attach Voltmeter. The voltmeter will have a small mounting bracket that needs to be attached in Connect Wire to Voltmeter. There are two connections at the back of the voltmeter where you will Locate Wire Harness. Remove the bottom of the dashboard and look for where the wire harness is. See all full list on doityourself How to Wire Voltmeter Gauges on a Car | It Still Runs How to Wire Voltmeter Gauges on a Car Use either butt connectors or the commonly supplied wire taps to connect the voltmeter wires to the wiring harness. Butt connectors are stronger and more reliable, but wire taps are faster and don't require cutting the original wire.