GM Service Manual Online
For 1990-2009 cars only

Removal Procedure


    Object Number: 221843  Size: MH
  1. Remove the Brake Modulator Assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement .
  2. Remove the Torx® head screws (5) attaching the gear cover.
  3. Remove the gear cover (4) from the Brake Motor pack (1).
  4. Remove the Torx® head screws (6) that attach the Brake Motor Pack (1) to the Hydraulic Modulator (2).
  5. Notice: Use care when handling the motor pack to avoid damaging the motor pack connector. Make sure brake fluid does not accidentally intrude into the motor pack. Brake fluid in the motor pack may cause a premature failure of the motor pack.

    Notice: Use care when handling the motor packs. Replace the motor packs if the motor packs are dropped or damaged during handling.

    Important: If the disassembly of the modulator assembly was caused by an ABS hydraulic functional test that did not pass, the Automated ABS brake motor pack Diagnosis Test should be performed. Refer to Scan Tool Diagnostics . The Automated ABS brake motor pack Diagnosis Test isolates the motor pack or brake modulator.

    Important: No repair of the motor pack is authorized. Replace as an assembly.

  6. Remove the Brake Motor Pack (1) from the Hydraulic Modulator (2).

Installation Procedure


    Object Number: 221843  Size: MH

    Important: Use care when handling the motor packs. Replace the motor packs if the motor packs are dropped or damaged during handling.

    Align each of the three motor pack pinions with the modulator gears.

  1. Install the Brake Motor Pack (1) to the Hydraulic Modulator (2).
  2. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the Torx® head screws (6) that attach the Brake Motor Pack (1) to the Hydraulic Modulator (2).
  4. Tighten
    Tighten the Torx® head screws to 5 N·m (44 lb in).

  5. Install the gear cover to the Brake Motor pack.
  6. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  7. Install the Torx® head screws attaching the gear cover.
  8. Tighten
    Tighten the Torx® head screws to 4 N·m (36 lb in).

  9. Install the Brake Modulator Assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement .
  10. Using the scan tool, perform the Motor Rehome Procedure.
  11. Perform the Diagnostic System Check - ABS .