Voltmeter immediately reads 18v or higher when powered on

The most common cause for this condition is when too many things connected to the volt-meter. On the back of many AutoMeter voltmeters, there are three terminals. These are identified with the letters “S”, “I”, and “GND”. Of these three terminals, only two are used. Connect the “GND” terminal to a common chassis ground, and connect the “I” terminal to a key-on power supply. Leave the “S” terminal empty. If you were to connect power to the “S” terminal, the gauge will immediately read at or above 18v. Simply remove your wire from the “S” terminal and the problem is solved.

The volt-meter uses the power (I) and ground (GND) terminals to measure the available volts. Running power to the sender (S) terminal skews the reading.

If you have nothing on the “S” terminal and the problem persists, you may then check the input to the gauge using a hand-held volt meter and measure across the “I” and “GND” terminals. What you measure here should match what the gauge reads. If it does not, you may contact our Service Department at 866-248-6357 for further assistance.