GM Service Manual Online
For 1990-2009 cars only

Step

Action

Yes

No

Schematic Reference: Shift Lock Control Schematics

Connector End View Reference: Computer/Integrating Systems Connector End Views

DEFINITION: Transmission shift lever does not lock in the PARK position with the ignition ON and the brake pedal not depressed.

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  1. Apply the parking brake and block the wheels.
  2. Turn ON the ignition, with the engine OFF.
  3. Attempt to move the shift lever out of the PARK position without pressing the brake pedal.

Does the shift lever move out of the PARK position?

Go to Step 3

Go to Testing for Intermittent Conditions and Poor Connections

3

  1. Turn OFF the ignition.
  2. Install a scan tool.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool observe the BTSI parameter in the body control module (BCM) data list.
  5. Ensure the brake pedal is not depressed.

Does the scan tool display a LOCKED status for the brake to shift parameter?

Go to Step 5

Go to Step 4

4

With a scan tool, observe the brake switch parameter in the EBCM data list.

Does the scan tool display a Released status for the brake switch parameter?

Go to Step 8

Go to Diagnostic Starting Point - Lighting Systems

5

  1. Turn OFF the ignition.
  2. Disconnect the automatic transmission (A/T) shift lock control solenoid electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Press and hold the brake pedal.
  5. Attempt to move the shift lever out of the PARK position.

Does the shift lever move out of the PARK position?

Go to Step 7

Go to Step 6

6

Test the A/T shift lock control solenoid control circuit for a short to power. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 8

7

Inspect for poor connections at the harness connector of the A/T shift lock control solenoid. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 9

8

Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 10

9

Replace the A/T shift lock control solenoid. Refer to Shift Lock Control Solenoid Replacement .

Did you complete the replacement?

Go to Step 11

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10

Replace the BCM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 11

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11

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2