Description and Operation: Voltmeter
WARNING: This page is about a different car, the 2003 GMC Sonoma, 2003 GMC Jimmy, 2003 Chevrolet S10 Pickup, and 2003 Chevrolet Blazer. However, it is still accessible from the selected car via links, so may be relevant.
The IPC displays the system voltage as detected at the ignition 1 voltage input of the IPC. When the engine is ON, the gage should be between 10 and 16 volts.