GM Service Manual Online
For 1990-2009 cars only
Battery Voltage Signal: The scan tool display 0.0-16 V. The battery voltage input represents the system voltage measured at the module ignition feed input.

Headlamp Washer Relay Status: The scan tool displays ON/OFF. When the instrument panel module (IPM) receives a wash input, it will activate the low side drive output that controls the headlamp washer relay and the scan tool will display the status of the relay as ON.

Headlamp Washer Switch: The scan tool displays ON/OFF. When the windshield wiper wash switch is pressed, the scan tool will display the switch input to the IPM as ON.