GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2000 🢒 GMC C-Series Medium Duty Truck B7 🢒 Brakes 🢒 Air Brakes 🢒 Rear Air Brake Relay Double Check Valve Replacement

Removal Procedure
  1. Apply the parking brake.
  2. Block the wheels.
  3. Drain all the reservoirs. Refer to Draining Reservoirs .
  4. Disconnect the air lines from the relay valve. Tag or label the air lines for installation.

    5. Object Number: 202743 Size: SH
  5. Remove the bolts (10).
  6. Remove the washers (8).
  7. Remove the nuts (7).
  8. Remove the relay valve with double check (3) from the frame.
  9. Inspect the air lines for damage, kinks or wear.

    10. Repair the lines as needed.

Installation Procedure

    Object Number: 202743 Size: SH
  1. Install the relay valve with double check (3).
  2. Install the bolts (10).
  3. Install the washers (8).

    4. 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.

  4. Install the nuts (7).

    5. Tighten
    Tighten the relay valve with double check nuts (7) to 45 N·m (33 lb ft).

  5. Install the air lines.
  6. Start the engine.
  7. Charge the system air pressure to the governor cut-out point.
  8. Stop the engine.
  9. Check for air leaks using a soap solution.
  10. Check for proper operation.
  11. Remove the wheel blocks.