GM Service Manual Online
For 1990-2009 cars only

Removal Procedure

  1. Apply the parking brake.
  2. Block the wheels.
  3. Drain all the reservoirs. Refer to Draining Reservoirs .
  4. Rotate the trailer air supply valve knob and the parking brake knob counter-clockwise to remove.
  5. Disconnect the air lines from the valve.
  6. Tag or label the air lines for later installation.

  7. Object Number: 894449  Size: SH
  8. Remove the valve assembly retaining screws.
  9. Remove the valve assembly.
  10. Inspect the air lines for damage or deterioration. Repair the air lines as needed.

Installation Procedure


    Object Number: 894452  Size: SH
  1. Install the valve.
  2. Install the knob.
  3. Start the engine.
  4. Charge the system air pressure to the governor cut-out point.
  5. Stop the engine.
  6. Check for air leaks using a soap solution.
  7. Check for proper operation.
  8. Remove the wheel blocks.