GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Control

1

1

2

--

Ground

--

1

--

--

1. Unable to move shift lever with brake level depressed.

2. Shift lever moves without brake pedal depressed.

Circuit/System Description

The body control module (BCM) controls the shift lock solenoid by providing battery voltage to the shift lock control solenoid. The BCM utilizes a smart driver to control the voltage supplied to the shift lock solenoid. The smart driver monitors the voltage and current flow of the control circuit.

Reference Information

Schematic Reference

Shift Lock Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic Transmission Shift Lock Control Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. Ignition ON, clear the DTC. Observe the scan tool BCM Stop Lamp Relay Command parameter while pressing and releasing the brake pedal. The parameter should change between ON and OFF.
  2. If the parameter does not change between the specified values, refer to Stop Lamps Malfunction.
  3. Press the brake pedal, the vehicle operator should be able to move the shifter out of the PARK position.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the shift lock control solenoid.
  2. Ignition OFF, test for less than 5.0 ohm between the ground circuit terminal B and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Install a test lamp between the ground circuit terminal B and the control circuit terminal A.
  5. Ignition ON, command the scan tool BCM Shift Lock Solenoid output control ON and OFF. The test lamp should turn ON and OFF as commanded.
  6. If the test lamp is always ON, test the control circuit for short to voltage. If the circuit tests normal, replace the BCM.
    If the test lamp is always OFF, test the control circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
  7. If the circuit tests normal, replace the transmission control.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Automatic Transmission Shift Lock Control Actuator Replacement
    •  Control Module References for BCM replacement, setup and programming