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Home >> GMC >> 2024 >> Hummer EV 2 >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> Hydraulic Brakes >> Repair Instructions >> Brake Master Cylinder Replacement - With Power Brake Booster and Electronic Brake Control Module >> Removal Procedure

Removal Procedure

  1. Prepare the brake system control module for removal. Control Module References
  2. WARNING:

    Always ensure the Battery Maintenance Mode is inactive before disconnecting the low voltage 12 volt battery (or batteries). This mode can be active with the ignition off, regardless of whether the vehicle charging cord is plugged in or not. When this mode is active, the on-board high voltage battery charger(s) will energize the 12 volt battery cables and charge the 12 volt battery (or batteries). Disconnecting any battery cables while this mode is active may result in an electrical shock or a burn from hot battery cable leads.

  3. Check the 12 volt battery voltage with a digital multimeter before disconnecting any battery cables leads. If the voltage is 13.5 volts or above, the Battery Maintenance Mode is active. The technician must wait for the T18 battery charger to deactivate before disconnecting the battery negative cable. Charging System Description and Operation
  4. Disconnect the battery negative cable. Battery Negative Cable Disconnection and Connection
  5. GM5835307Courtesy of GENERAL MOTORS COMPANY

    Brake Pedal Push Rod Bolt (1) - Remove

  6. Brake Pedal Nut (2) - Remove [4x]
  7. GM5787985Courtesy of GENERAL MOTORS COMPANY

    Turn the 3 front compartment sight shield retainers (1) a quarter turn counter clockwise to release.

  8. GM5787987Courtesy of GENERAL MOTORS COMPANY

    Front Compartment Side Sight Shield (1) - Remove

  9. Thoroughly clean the brake master cylinder reservoir and the brake master cylinder body to remove any dirt and debris.
  10. Electrical Connector @ Brake System Control Module - Disconnect
  11. Electrical Connector @ Brake Fluid Level Indicator Switch - Disconnect
  12. Place a drain pan under the vehicle.
  13. GM5835315Courtesy of GENERAL MOTORS COMPANY

    Brake Master Cylinder Bolt (1) - Remove [2x]

  14. GM5835316Courtesy of GENERAL MOTORS COMPANY

    Brake Master Cylinder Reservoir (1) - Remove

  15. Brake Master Cylinder Reservoir Seal (2) - Remove and DISCARD [3x]
  16. GM5835311Courtesy of GENERAL MOTORS COMPANY

    Remove the 4 rear brake front pipe nuts (1) and position the brake pipes aside.

  17. GM5835308Courtesy of GENERAL MOTORS COMPANY

    Brake Master Cylinder Adapter Nut (1) - Remove

  18. GM5898955Courtesy of GENERAL MOTORS COMPANY
    NOTE:

    Disconnecting the wiring harness is not required to complete these steps.

    Chassis Control Module Bracket Nut (2) - Remove

  19. Chassis Control Module Bracket Bolt (1) - Remove [2x]
  20. Chassis Control Module Bracket (3) - Reposition away
  21. GM5898954Courtesy of GENERAL MOTORS COMPANY

    Drive Motor Battery Radiator Surge Tank Bolt (1) - Remove

  22. Drive Motor Battery Radiator Surge Tank (2) - Reposition
  23. GM5835312Courtesy of GENERAL MOTORS COMPANY

    Maneuver the brake master cylinder (1) out of the vehicle.

  24. Brake Master Cylinder Gasket (2) - Remove and DISCARD
  25. Clean any brake fluid from the underbody area and remove the drain pan from under the vehicle.