Voltmeter Reads 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 gauge should read 12 volts or more.
If gauge does not read 12 volts or more, check for high resistance in voltmeter gauge terminal connections. Clean and tighten connections.
If voltmeter reading is still low, apply 12 volts directly to positive terminal of gauge. If voltmeter does not respond accurately, replace gauge.