Power Brake Booster Pressure Sensor Replacement

Power Brake Booster Pump Fluid Accumulator Replacement (Two-mode Hybrid)

Removal Procedure


Warning

The high pressure accumulator (HPA) and the chambers of the brake modulator assembly to which it attaches, store brake fluid at extremely high pressures. Fluid pressure must be relieved before attempting to service the HPA. Ensure that the recommended procedures are followed to relieve system pressure, including using the manual pressure release steps. Failure to properly follow procedures to depressurize the system may result in personal injury.

Warning: Refer to Brake Fluid Irritant Warning (Brake Fluid Irritant Warning) .

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution (Vehicle Damage Warnings) .



Note

The ignition must be in the OFF position, without pausing at ACCESSORY, and without applying the brake pedal to ensure the brake modulator and high pressure accumulator (HPA) pressure relief occurs. This process will take approximately 1 to 3 minutes.

1. Turn the ignition to OFF, without pausing at ACCESSORY, and remove the ignition key.
2. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle (Service and Repair) .




3. Clean any dirt and debris from the brake modulator assembly and the HPA.


Note

To ensure brake modulator and HPA pressure relief has occurred, the manual pressure relief valve must be opened momentarily.

4. Loosen the manual pressure relief valve (1) 1/4 turn counterclockwise.
5. Seat, but do not tighten, the manual pressure relief valve.


Note

Adequately support the brake modulator assembly to avoid placing stress on the brake pipes and hoses.

6. Without disconnecting the brake pipes and hoses, remove the brake pressure modulator assembly bracket. Refer to Brake Pressure Modulator Valve Replacement (Service and Repair) .




7. Remove the HPA (1).




8. Remove and discard the HPA O-ring seal (1).
9. Remove any debris from the O-ring seal groove in the brake modulator assembly with a clean, lint-free shop cloth.
10. If replacing the HPA, properly render inert and dispose of the HPA. Refer to Power Brake Booster Pump Fluid Accumulator Disposal (Procedures) .



Installation Procedure





1. Lubricate a new O-ring seal (1) with Delco Supreme 11(R), GM P/N 12377967 (Canadian P/N 992667), or equivalent DOT-3 brake fluid from a clean, sealed brake fluid container.
2. Install the O-ring seal to the HPA. Ensure the seal is fully seated in the groove of the HPA and is not twisted.




Caution: Refer to Fastener Caution (Fastener Caution) .
3. Install the HPA (1) to the brake modulator assembly and tighten to 30 Nm (22 lb ft) .
4. Install the brake modulator assembly bracket and remove the support. Refer to Brake Pressure Modulator Valve Replacement (Service and Repair) .




5. Tighten the brake modulator manual pressure relief valve (1) to 40 Nm
(30 lb ft) .
6. Perform theAntilock Brake System Automated Bleed Procedure (Service and Repair) . Follow the procedure completely to ensure the learn procedure for the pressure and travel sensors has occurred.