Are we talking about a voltmeter or an ammeter? The voltmeter is easy- - - -just connect it across the terminals of the battery, and it will indicate the voltaqge if it's in good shape. An ammeter needs current flowing to show a reading, so it needs to be in series with the circuit you're using. Is the gauge installed, or out of the truck? If it's in the dash and the wiring harness is intact, disconnect the wire at the "Bat" terminal of the voltage regulator and attach a battery charger red connector to the wire, and the black connector to ground. Turn the charger on, and the ammeter should show a charge. Connect a headlight bulb to that wire and ground, and the gauge will show a discharge.
If the ammeter is out of the truck, the same procedure will work, just put the gauge in the circuit so the current has to flow through it to do the charge/discharge thing.
Jerry
