GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Ignition 0: Displays 0.0-25.5 V. This parameter is the system voltage measured by the BCM at the BCM battery input.

Ignition 1: Displays 0.0-25.5 V. This parameter is the system voltage measured by the BCM at the BCM ignition 1 voltage input.

Park (BTSI) Relay: Displays indicates ON when the body control module applies a ground to the automatic transmission shift lock control solenoid.