Voltmeter Indicates 9 Volts Or Less

Measure voltage across battery terminals. Voltage should be about 12 volts. If battery is discharged, recharge battery, and perform load test. Repair cause of discharged battery.
With ignition on and battery terminals cleaned and connected, observe voltmeter with battery charger in operation. Voltmeter should indicate 12 volts or more.
If gauge does not indicate 12 volts or more, check for high resistance in voltmeter terminal connections. Clean and tighten connections.
If voltmeter indication is still low, apply battery voltage directly to positive terminal of gauge. If voltmeter does not respond accurately, replace cluster.