When the vehicle is in accessory mode, the voltmeter shows the voltage output of the battery. When the engine is running, it shows the voltage output of the charging system.

The reading will change as the rate of charge changes (with engine speed, for example), but if the voltmeter reads at 9 volts or below, the instrument panel cluster and other systems may shut down. The Driver Information Center (DIC) will read LOW VOLTAGE when the vehicle is at 10 volts or below. Have it checked right away. Driving with the voltmeter reading at 10 volts or below could drain the battery and disable the vehicle.