GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Battery 1: The scan tool displays 0 - 20 volts. The scan tool displays the voltage as received on the battery positive voltage circuit of the body control module (BCM).

TR Sw.: The scan tool displays Reverse, Intermediate, Drive, Park, Neutral and Low. The scan tool displays the position of the transaxle switch.

Shifter Unlock Fdbk: The scan tool displays Low/High. The scan tool displays Low when the mechanical lock is engaged preventing an inadvertent shift out of the PARK position. The scan tool displays High when the BCM opens the controlled ground circuit of the shift lock control solenoid.

Powertrain Control Module (PCM)

Brake Switch: The scan tool displays Released/Applied. The scan tool displays the status of the brake switch.