GM Service Manual Online
For 1990-2009 cars only

Body Control Module (BCM)

Battery Voltage Signal: The scan tool displays 0 - 20 Volts. The scan tool displays the voltage as received by the body control module (BCM).

Shift Lock Solenoid Command: The scan tool displays Lock/Unlock. The scan tool displays the status of the shift lock control solenoid. Lock indicates that the BCM has applied 12 volts to the control circuit. Unlock indicates that the BCM has removed 12 volts from the control circuit.

Engine Control Module (ECM)

BPP Circuit Signal: The scan tool displays Applied/Release. The scan tool displays the status of the brake pedal position (BPP) switch.

Transmission Control Module (TCM)

IMS: The scan tool displays, Drive 3, Drive 4\Drive 3, Park\Reverse, Reverse, Drive 3\Drive 2, Drive 2, Park, Invalid, Neutral\Drive 4, Drive 4, Neutral, Reverse\Neutral, Drive 1, Drive 2\Drive 1 or Open. The scan tool displays the status of the transmission internal mode switch (IMS).

TCC Brake Switch: The scan tool displays Open/Closed. The scan tool displays the status of the torque converter clutch (TCC) brake switch.

TR Sw. : The scan tool displays Park, Reverse, Neutral, Drive 5, Drive 4, Drive 3, Drive 2 or Drive 1. The scan tool displays the state of the transmission range switch.