GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2009 🢒 Yukon Denali 🢒 Preface 🢒 Dangers, Warnings, and Cautions 🢒 Master Cylinder Replacement

Master Cylinder Replacement JD9


Object Number: 1850408 Size: MF

Callout

Component Name

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

Preliminary Procedures

  1. With the engine OFF, apply the brake pedal several times until the brake pedal becomes firm to deplete the vacuum brake booster vacuum reserve.
  2. Using a suitable tool, remove the brake fluid from the brake master cylinder reservoir.
  3. Discard the brake fluid into an approved container.

1

Master Cylinder Fluid Level Sensor Electrical Connector

2

Brake Pipe Fitting (Qty: 2)

Caution: Refer to Fastener Caution in the Preface section.

Procedure

  1. Remove any dirt or debris from the brake pipe fitting.
  2. Cap the brake pipe fittings to prevent brake fluid loss and contamination.

Tighten
32 N·m (24 lb ft)

3

Brake Master Cylinder Nut (Qty: 2)

Tighten
36 N·m (27 lb ft)

4

Brake Master Cylinder Assembly

5

Brake Master Cylinder to Vacuum Booster Seal

Procedure

  1. Inspect the brake master cylinder to vacuum booster seal for damage and replace if necessary.
  2. Ensure the brake master cylinder to vacuum booster seal is properly seated against the base of the brake master cylinder.

    3. Do not place the brake master cylinder to vacuum booster seal in the groove of the master cylinder body.

  3. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding.

Master Cylinder Replacement JH6


Object Number: 1850419 Size: MF

Callout

Component Name

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

Preliminary Procedures

  1. Using a suitable tool, remove the brake fluid from the brake master cylinder reservoir.
  2. Discard the brake fluid into an approved container.
  3. Disconnect the brake fluid pressure sensor electrical connector, if equipped.

1

Master Cylinder Fluid Level Sensor Electrical Connector

2

Brake Pipe Fitting (Qty: 2)

Caution: Refer to Fastener Caution in the Preface section.

Procedure

  1. Remove any dirt or debris from the brake pipe fitting.
  2. Cap the brake pipe fittings to prevent brake fluid loss and contamination.

Tighten
32 N·m (24 lb ft)

3

Brake Master Cylinder Nut (Qty: 2)

Tighten
36 N·m (27 lb ft)

4

Brake Master Cylinder Assembly

Procedure

  1. Remove and discard the push-on nuts on the master cylinder mounting studs, if equipped.
  2. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding.

Master Cylinder Replacement Two-mode Hybrid

Removal Procedure

Warning: Refer to Brake Fluid Irritant Warning in the Preface section.

Caution: Refer to Brake Fluid Effects on Paint and Electrical Components Caution in the Preface section.

    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. Note: During the pressure relief process, the fluid level in the master cylinder reservoir will rise. Do not remove the master cylinder reservoir cap during the pressure relief process.

  2. Wait approximately 1 to 3 minutes until the brake modulator and HPA pressure relief is complete.
  3. Remove the brake fluid from the brake master cylinder reservoir and discard into an approved container.
  4. Disconnect the brake fluid level sensor electrical connector.

    5. Object Number: 1892190 Size: SH
  5. Disconnect the brake master cylinder reservoir return hose quick connect (1) and position the hose aside.
  6. Disconnect the brake master cylinder reservoir supply hose quick connect (2) and position the hose aside.

    7. Object Number: 1892200 Size: SH
  7. Disconnect the brake master cylinder primary brake pipe fitting (1).

    8. Cap the brake pipe fitting and plug the master cylinder outlet port to prevent brake fluid loss and contamination.


    Object Number: 1892202 Size: SH
  8. Disconnect the brake master cylinder left supply brake pipe fitting (1).

    9. Cap the brake pipe fitting and plug the master cylinder outlet port to prevent brake fluid loss and contamination.


    Object Number: 1892213 Size: SH
  9. Disconnect the brake master cylinder right supply brake pipe fitting (1).

    10. Cap the brake pipe fitting and plug the master cylinder outlet port to prevent brake fluid loss and contamination.


    Object Number: 1892216 Size: SH
  10. Disconnect the brake master cylinder right front brake pipe fitting (1).

    11. Cap the brake pipe fitting and plug the master cylinder outlet port to prevent brake fluid loss and contamination.


    Object Number: 1892220 Size: SH
  11. Disconnect the brake master cylinder left front brake pipe fitting (1).

    12. Cap the brake pipe fitting and plug the master cylinder outlet port to prevent brake fluid loss and contamination.


    Object Number: 1892240 Size: SH
  12. Remove the brake master cylinder nuts (1).

    13. Discard the brake master cylinder nuts.


    Object Number: 1892241 Size: SH
  13. Remove the brake master cylinder and the master cylinder seal (1).

Installation Procedure
  1. Bench bleed the master cylinder. Refer to Master Cylinder Bench Bleeding.

    2. Object Number: 1892241 Size: SH
  2. Install the brake master cylinder seal (1) and the master cylinder to the adapter.

    3. Ensure the brake master cylinder seal is fully seated in the groove on the master cylinder housing.

    Caution: Refer to Fastener Caution in the Preface section.


    Object Number: 1892240 Size: SH
  3. Install 2 new brake master cylinder nuts (1) and tighten to  33 N·m (24 lb ft).

    4. Object Number: 1892220 Size: SH
  4. Connect the brake master cylinder left front brake pipe fitting (1) and tighten to  30 N·m (22 lb ft).

    5. Object Number: 1892216 Size: SH
  5. Connect the brake master cylinder right front brake pipe fitting (1) and tighten to  30 N·m (22 lb ft).

    6. Object Number: 1892213 Size: SH
  6. Connect the brake master cylinder right supply brake pipe fitting (1) and tighten to  30 N·m (22 lb ft).

    7. Object Number: 1892202 Size: SH
  7. Connect the brake master cylinder left supply brake pipe fitting (1) and tighten to  30 N·m (22 lb ft).

    8. Object Number: 1892200 Size: SH
  8. Connect the brake master cylinder primary brake pipe fitting (1) and tighten to  30 N·m (22 lb ft).

    9. Object Number: 1892190 Size: SH
  9. Connect the brake master cylinder reservoir return hose quick connect (1).
  10. Connect the brake master cylinder reservoir supply hose quick connect (2).
  11. Connect the brake fluid level sensor electrical connector.
  12. Fill the brake master cylinder reservoir. Refer to Master Cylinder Reservoir Filling.
  13. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding.