GM Service Manual Online
For 1990-2009 cars only

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

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

Notice: Always connect or disconnect the wiring harness connector from the EBCM/EBTCM with the ignition switch in the OFF position. Failure to observe this precaution could result in damage to the EBCM/EBTCM.

Removal Procedure


    Object Number: 1233230  Size: SH
  1. Turn the ignition switch to the OFF position.
  2. Clean the brake modulator assembly pipe fitting areas of any accumulated dirt and foreign material.
  3. Disconnect the electrical connector from the electronic brake control module (EBCM).
  4. Remove the EBCM. Refer to Electronic Brake Control Module Replacement .

  5. Object Number: 1234780  Size: SH
  6. Place a shop towel under the brake modulator assembly to catch any brake fluid loss.
  7. Important: Prior to disconnecting the brake pipes from the ABS modulator assembly, note the locations of the brake pipes to the valve assembly, to aid during installation.

  8. Disconnect the 4 brake pipes (2) from the brake pressure modulator valve (BPMV).
  9. Cap the brake pipe ends to prevent brake fluid loss and contamination.
  10. Disconnect the master cylinder brake pipes (1) from the BPMV.
  11. Cap the brake pipe ends to prevent brake fluid loss and contamination.
  12. Plug the modulator brake pipe openings to prevent brake fluid loss and contamination.

  13. Object Number: 1234794  Size: SH
  14. Remove the 4 insulator bolts on the brake pressure modulator valve bracket.
  15. Remove the brake modulator valve from modulator bracket by pulling straight up.

Installation Procedure

Important: When installing a new brake modulator assembly, do NOT remove the shipping plugs from the pipe ports until after installation into the vehicle.

  1. Install the brake modulator valve to the modulator bracket.
  2. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 1234794  Size: SH
  3. Install the 4 brake pressure modulator valve bracket insulator bolts.
  4. Tighten
    Tighten the bolts to 10 N·m (89 lb in).


    Object Number: 1234780  Size: SH
  5. Remove the caps from the master cylinder brake pipe ends.
  6. Connect the master cylinder brake pipes (1) to the modulator assembly, in the same location as removed.
  7. Remove the caps from the caliper and wheel cylinder brake pipe ends.
  8. Remove the plugs from the caliper and wheel cylinder ports on the modulator assembly.
  9. Connect the  4 brake pipes (2) to the modulator valve, in the same location as removed.
  10. Tighten all the brake pipe fittings at the BPMV.
  11. Tighten
    Tighten the brake pipe fittings to 20 N·m (15 lb ft).

  12. Install the EBCM. Refer to Electronic Brake Control Module Replacement .

  13. Object Number: 1233230  Size: SH

    Important: Ensure that the electrical connector is correctly inserted properly into the EBCM prior to swinging the assist locking lever into position. Failure to make a proper connection may cause communication problems with the module.

  14. Connect the electrical connector to the EBCM.
  15. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding .
  16. Important: Do NOT start the engine, but only turn the ignition switch to the ON position.

  17. Perform the Diagnostic System Check - Vehicle .
  18. Observe the feel of the brake pedal after performing the diagnostic system check. If the pedal now feels spongy, air may have been in the secondary circuit of the brake modulator assembly, which may have been introduced into the primary circuit. If the pedal feels spongy, perform the Antilock Brake System Automated Bleed Procedure .
  19. Remove the shop towel and discard into an approved container.