Hydraulic System Junction Block: Service and Repair

Brake Pipe Manifold Replacement

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 Brake Fluid Effects on Paint and Electrical Components Caution.

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. Remove the brake pressure modulator valve assembly. Refer to Brake Pressure Modulator Valve Replacement Service and Repair.





4. Remove the master cylinder return hose fitting (1).

5. Remove the master cylinder supply hose fitting (2).

6. Remove and discard the O-ring seals (3).





7. Remove the brake pipe manifold bolts (1).





8. Remove the brake pipe manifold (1).





9. Remove the 5 transfer tubes (1).

10. Remove and discard the 5 upper transfer tube O-ring seals (2).

11. Remove discard the 5 lower transfer tube O-rings seals (3).

Installation Procedure





1. Assemble the 5 transfer tubes (1) to 5 new upper transfer tube O-ring seals (2).

2. Install the 5 new lower transfer tube O-ring seals (3).

3. Lubricate the new O-ring seals 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.

4. Install the transfer tube assemblies to the brake modulator valve assembly.





5. Install the brake pipe manifold (1).





Caution:
Refer to Fastener Caution Fastener Caution.

6. Install the brake pipe manifold bolts (1).

Tighten the bolts to 11 Nm (97 lb in).





7. Assemble the master cylinder return hose fitting (1) and the master cylinder supply hose fitting (2) to the new O-ring seals (3).

8. Lubricate the new O-ring seals 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.

9. Install the return and supply hose fittings to the brake modulator valve assembly.

Tighten the fittings to 8 Nm (71 lb in).

10. Install the brake modulator assembly. Refer to Brake Pressure Modulator Valve Replacement Service and Repair.