Shifting problem

Hi,

I have an odd question. Do the brake lights work when it won't shift? The park lock actuator is powered when the brakes are applied. So, first check that. If they work, here are the diagnostics. These do require a scan tool and some basic electrical checking tools.

Here is a link you may find helpful:

https://www.2carpros.com/articles/how-to-check-wiring

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Circuit/System Verification

1. Ignition ON, while pressing the brake pedal, observe the scan tool Brake Applied Output Signal parameter. The reading should be ON with the brake pedal pressed.

- If not the specified value, refer to Stop Lamps Inoperative. See: Lighting and Horns > Symptom Related Diagnostic Procedures > Stop Lamps Inoperative

2. 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 OFF, disconnect the harness connector at the Automatic Transmission Shift Lever assembly.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal B and ground.

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

3. While pressing the brake pedal, verify that a test lamp illuminates between the control circuit terminal A and ground.

- If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If all circuits test normal, test or replace the BCM.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. See: Lighting and Horns > Symptom Related Diagnostic Procedures > Stop Lamps Inoperative

* Automatic Transmission Shift Lock Actuator Replacement
* Refer to Programming and Relearning for BCM replacement setup and programming.See: Vehicle > Programming and Relearning
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If you find the actuator is the issue, here are the directions for replacement. The attached pics correlate with the directions.

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2007 Buick Lucerne V6-3.8L
Automatic Transmission Shift Lock Actuator Replacement
Vehicle Powertrain Management Transmission Control Systems Actuators and Solenoids - Transmission and Drivetrain Actuators and Solenoids - A/T Shift Interlock Solenoid Service and Repair Removal and Replacement Automatic Transmission Shift Lock Actuator Replacement
AUTOMATIC TRANSMISSION SHIFT LOCK ACTUATOR REPLACEMENT
Automatic Transmission Shift Lock Actuator Replacement

Removal Procedure

1. Remove the knee bolster.
2. Remove the steering column trim covers.

pic 1

3. Disconnect the automatic transmission shift lock control connector.

pic 2

4. Use a screwdriver to pry the automatic transmission shift lock control from the steering column support assembly.
5. Remove the automatic transmission shift lock control from the steering column.

Installation Procedure

pic 3

1. Install the automatic transmission shift lock control.
Put the column in the NEUTRAL position.

pic 4

2. Adjust the automatic transmission shift lock control.

1. Pull the tab (1) out on the block side (2) of the automatic transmission shift lock control.
2. Shift the column into the NEUTRAL position.
3. Press on the adjuster block (2) to compress the internal adjuster spring to disengage the adjuster teeth. Slide the adjuster block (2) as far away from the solenoid as possible.
4. Shift the column into the PARK position.
5. Lock in place by pushing the tab (1) back in.

3. Inspect the automatic transmission shift lock control.

pic 5

4. Reconnect the automatic transmission shift lock control connector.
5. Install the steering column trim covers.
6. Install the knee bolster.

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I hope this helps. Let me know if you have other questions.

Take care,
Joe