Vacuum Brake Booster: Service and Repair

Power Vacuum Brake Booster Replacement

Removal Procedure

1. Place the vehicle on a level surface and apply the park brake.

2. With the engine OFF, apply and release the brake pedal several times until the brake pedal becomes firm to deplete the vacuum reserve in the vacuum brake booster.

3. Remove the air cleaner housing cover and duct. Refer to Air Cleaner Element Replacement Service and Repair.

4. Disconnect the brake fluid level indicator switch electrical connector.




5. Remove the power brake booster vacuum check valve and hose assembly (1) from the brake booster and position aside.




6. Disconnect the power brake booster vacuum sensor electrical connector.

7. Remove the power brake booster vacuum sensor (1).




8. Release the front and rear brake pipes (1) from the routing clip on the frame rail.

9. Remove the 2 nuts (2) from the brake pressure modulator valve (BPMV) assembly.

Note: It is not necessary to disconnect the brake pipes from the BPMV assembly.

10. Carefully lift the BPMV assembly over the studs and position forward slightly.




11. Remove the master cylinder nuts (1).

Note: It is not necessary to disconnect the brake pipes from the master cylinder.

12. Without disconnecting the brake pipes from the master cylinder, remove the master cylinder assembly and position aside.

13. Place the brake master cylinder in an upright position and support with heavy mechanics wire or equivalent.




14. Remove the left side instrument panel insulator panel. Refer to Instrument Panel Insulator Panel Replacement - Left Side (Enclave) Instrument Panel Insulator Panel Replacement - Left SideInstrument Panel Insulator Panel Replacement - Left Side (Acadia) Instrument Panel Insulator Panel Replacement - Left SideInstrument Panel Insulator Panel Replacement - Left Side (Traverse) Instrument Panel Insulator Panel Replacement - Left Side.

15. Remove the driver knee bolster. Refer to Driver Knee Bolster Replacement (Acadia) Service and RepairDriver Knee Bolster Replacement (Traverse) Service and RepairDriver Knee Bolster Replacement (Enclave) Service and Repair.

16. Remove the brake pedal pushrod retaining clip (1).

17. Remove the brake pedal pushrod clevis pin (2) and disconnect the pushrod from the brake pedal.

18. Remove the intermediate steering shaft. Refer to Intermediate Steering Shaft Replacement Intermediate Steering Shaft Replacement.




19. Remove the 4 vacuum brake booster nuts.




20. Pull the vacuum brake booster forward and tilt upward slightly until the mounting studs clear the dash panel.

21. Remove the vacuum brake booster.

Installation Procedure





Note: Inspect the vacuum brake booster to dash panel gasket for damage and replace, if necessary.

1. Align the vacuum brake booster mounting studs to the dash panel.

2. Install the vacuum brake booster.





Caution: Refer to Fastener Caution Fastener Caution.

3. Install the 4 vacuum brake booster nuts and tighten to 25 Nm (18 lb ft).

4. Install the intermediate steering shaft. Refer to Intermediate Steering Shaft Replacement Intermediate Steering Shaft Replacement.




5. Connect the brake pedal pushrod to the brake pedal and install the clevis pin (2).

6. Install the brake pedal pushrod retaining clip (1).

7. Install the driver knee bolster. Refer to Driver Knee Bolster Replacement (Acadia) Service and RepairDriver Knee Bolster Replacement (Traverse) Service and RepairDriver Knee Bolster Replacement (Enclave) Service and Repair.

8. Install the left side instrument panel insulator panel. Refer to Instrument Panel Insulator Panel Replacement - Left Side (Enclave) Instrument Panel Insulator Panel Replacement - Left SideInstrument Panel Insulator Panel Replacement - Left Side (Acadia) Instrument Panel Insulator Panel Replacement - Left SideInstrument Panel Insulator Panel Replacement - Left Side (Traverse) Instrument Panel Insulator Panel Replacement - Left Side.

9. Inspect the master cylinder to vacuum brake booster seal for damage and replace, if necessary.





Note: Ensure the master cylinder to vacuum brake booster seal is properly installed on the back of the master cylinder housing and is not damaged.

10. Position the master cylinder to the vacuum booster.

11. Install the master cylinder nuts (1) and tighten to 20 Nm (15 lb ft).




12. Position the BPMV assembly over the studs.

13. Install the 2 nuts (2) to the BPMV and bracket assembly and tighten to 20 Nm (15 lb ft).

14. Install the front and rear brake pipes (1) to the routing clip on the frame rail.





Note: A small amount of denatured alcohol may be used as a lubricant for assembly. Do not use soap.

15. Install the power brake booster vacuum sensor (1).

16. Connect the power brake booster vacuum sensor electrical connector.





Note: A small amount of denatured alcohol may be used as a lubricant for assembly. Do not use soap.

17. Install the power brake booster vacuum check valve and hose assembly (1) to the brake booster.

18. Connect the brake fluid level indicator switch electrical connector.

19. Install the air cleaner housing cover and duct. Refer to Air Cleaner Element Replacement Service and Repair.