Transmission Control Lever Malfunction

Transmission Control Lever Malfunction

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.



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.


Diagnostic Fault Information






Reference Information
Schematic Reference

Shift Lock Control Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views
Description and Operation

Automatic Transmission Shift Lock Control Description and Operation (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, with the brake pedal applied, observe the scan tool Stop Lamp Relay Command parameter. The reading should be ON with the brake pedal depressed and released.

• If not the specified parameter, refer to Stop Lamps Malfunction (Chevy, GMC) Stop Lamps Malfunction (Cadillac non EXP) Stop Lamps Malfunction (Cadillac EXP) .

2. Ignition ON, observe the scan tool BCM shift lock solenoid command parameter. The parameter should change from ON to OFF when the brake pedal is applied and released.

• If not the specified parameter, replace the BCM.

3. Press the brake pedal, the vehicle operator should be able to move the shifter lever out of the park position.



Circuit/System Testing

1. Ignition ON, with the brake pedal applied, observe the scan tool Stop Lamp Relay Command parameter. The reading should be ON with the brake pedal depressed.

• If not the specified parameter, refer to Stop Lamps Malfunction (Chevy, GMC) Stop Lamps Malfunction (Cadillac non EXP) Stop Lamps Malfunction (Cadillac EXP) .

2. Ignition OFF, disconnect the harness connector at the automatic transmission shift lock actuator.
3. Ignition OFF, test for less than 1.0 ohm between the ground circuit terminal B and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

4. Connect a test lamp between the control circuit terminal A and ground.
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.

• If the test lamp is always ON, test the control circuit for a short to voltage. If circuit test normal, replace the BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If circuits test normal, replace the BCM.

6. If all circuits test normal, test or replace the shift lock actuator.



Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

* Automatic Transmission Shift Lock Actuator Replacement (Service and Repair)
* Control Module References for BCM replacement, setup and programming