GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 1997 🢒 GMC P62 Commercial Chassis 🢒 Brakes 🢒 Park Brake 🢒 Park Brake Valve

Operational Check
  1. Block the vehicle's wheels.
  2. Start the engine.
  3. Charge the system to about 860 kPa (125 psi).
  4. Pull out the park brake valve knob and release the brake pedal.
  5. Verify that the park brake actuator assembly is applied.
  6. Push in the park brake valve knob.
  7. Verify that the park brake actuator assembly is fully released.
  8. Drain the system #1 tank.
  9. Observe the system #1 gauge while the tank is draining.
  10. Verify that the park brake valve knob pops out when the air pressure is below 414 kPa (60 psi).

    11. Repair or replace the valve if the knob does not pop out.

  11. Remove the wheel blocks.

Leakage Test
  1. Block the vehicle's wheels.
  2. Start the engine.
  3. Charge the system to about 860 kPa (125 psi).
  4. Pull out the park brake valve knob in order to release the brake pedal.
  5. Apply a soap solution to the exhaust port.
  6. Check the exhaust port for leakage. Slight leakage is permitted.

    7. Repair or replace the valve if leakage is excessive.

  7. Push in the park brake valve knob.
  8. Remove the wheel blocks.