GM Service Manual Online
For 1990-2009 cars only

Object Number: 900989  Size: SH

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: There is a first design and second design of brake pipe flare for the hydraulic brake pipes and system components used on this vehicle. Do NOT mis-match flare types. If the flare types are mis-matched, damage to the pipes and/or components, and/or a brake fluid leak may occur.

   • First design, ISO flare (1)
   • Second design, double inverted flare (2)

Removal Procedure


    Object Number: 890974  Size: SH
  1. Place a shop towel under the proportioning valve assembly to catch any brake fluid loss.
  2. Important: Prior to disconnecting the brake pipes from the proportioning valve assembly, note the locations of the brake pipes to the valve assembly, to aid during installation.

  3. Disconnect the caliper and wheel cylinder brake pipes (1) from the proportioning valve assembly.
  4. Cap or plug the brake pipe ends to prevent brake fluid loss and contamination.
  5. Disconnect the master cylinder brake pipes (2) from the proportioning valve assembly.
  6. Cap or plug the brake pipe ends to prevent brake fluid loss and contamination.
  7. If the proportioning valve is to be reused, plug the ports to prevent brake fluid loss and contamination.

  8. Object Number: 890977  Size: SH
  9. Release the forward lamp wiring harness from the proportioning valve assembly bracket.
  10. Remove the proportioning valve assembly bracket mounting nut and mounting bolt.
  11. Remove the proportioning valve assembly from the vehicle.

Installation Procedure


    Object Number: 890977  Size: SH
  1. Install the proportioning valve assembly to the vehicle.
  2. Notice: Refer to Fastener Notice in the Preface section.

  3. Install the proportioning valve assembly bracket mounting nut and mounting bolt.
  4. Tighten

        • Tighten the nut to 25 N·m (18 lb ft).
        • Tighten the bolt to 25 N·m (18 lb ft).
  5. Secure the forward lamp wiring harness to the proportioning valve assembly bracket.

  6. Object Number: 890974  Size: SH
  7. Remove the plugs from the proportioning valve assembly ports.
  8. Remove the caps or plugs from the master cylinder brake pipe ends.
  9. Connect the master cylinder brake pipes (2) to the proportioning valve assembly.
  10. Tighten the brake pipe fittings at the proportioning valve assembly.
  11. Tighten

        • Tighten the fittings, first design, ISO flare to 19 N·m (14 lb ft).
        • Tighten the fittings, second design, double inverted flare to 18 N·m (13 lb ft).
  12. Remove the caps or plugs from the caliper and wheel cylinder brake pipe ends.
  13. Connect the caliper and wheel cylinder brake pipes (1) to the proportioning valve assembly.
  14. Tighten the brake pipe fittings at the proportioning valve assembly.
  15. Tighten

        • Tighten the fittings, first design, ISO flare to 19 N·m (14 lb ft).
        • Tighten the fittings, second design, double inverted flare to 18 N·m (13 lb ft).
  16. Bleed the hydraulic brake system. Refer to Hydraulic Brake System Bleeding .
  17. Remove the shop towel and discard into an approved container.