GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

  1. Block the wheels.
  2. Drain all of the air reservoirs. Refer to Air Brake Reservoir Draining .
  3. Remove the air lines from the relay valve. Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .
  4. Tag or label the lines for installation.
  5. Remove the following components:
  6. • The nuts
    • The washers
    • The bolts

    Object Number: 227932  Size: SH
  7. Remove the relay valve right side.

  8. Object Number: 227935  Size: SH
  9. Remove the relay valve left side.
  10. Inspect the air lines for the following conditions:
  11. • Damage
    • Kinks
    • Wear
  12. Replace any damaged, kinked, or worn air lines.

Installation Procedure


    Object Number: 227932  Size: SH
  1. Install the relay valve left side.
  2. Notice: Refer to Fastener Notice in the Preface section.


    Object Number: 227935  Size: SH
  3. Install the relay valve right side.
  4. Tighten
    Tighten the relay valve bolts to 52 N·m (38 lb ft).

  5. Install the air lines to the relay valve. Refer to Hose and Line Replacement - Nylon Push-In Type Fitting .
  6. Perform the air leakage test. Refer to Rear Air Brake Relay Valve Operational Check .
  7. Perform the operational test. Refer to Rear Air Brake Relay Valve Leakage Test .
  8. Remove the wheel blocks.