GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 28662 Brake Pedal Effort Gauge

  1. Release the brake pedal.
  2. Start the engine.
  3. Press the brake pedal fully.
  4. With the brake pedal pressed, turn the ignition switch to LOCK.
  5. Inspect the pedal travel. If there is no change in pedal travel, the booster is airtight. The booster is OK.
  6. If brake pedal travel exists after the engine is turned off, complete the following procedure:
  7. 6.1. Install a check valve and hose that are known to be operating properly.
    6.2. Repeat the first four steps.
    6.3. If there is no change in the pedal travel, replace the check valve and the hose.
    6.4. If brake pedal travel exists, replace the booster assembly. Refer to Power Vacuum Brake Booster Replacement .
  8. Start the engine for 15 seconds.
  9. Turn the ignition switch to LOCK.
  10. Pump the brake pedal until all the reserve is exhausted from the booster.
  11. Use the J 28662 in order to press the brake pedal with a force of 294 N (66 lbs).
  12. With the brake pedal pressed, start the engine.
  13. Inspect the brake pedal. If the brake pedal moves slightly to the floor, a reserve brake pedal distance is present. The booster is functioning normally.
  14. If the brake pedal does not move slightly to the floor, complete the following procedures:
  15. 13.1. Install a check valve and hose that are known to be operating properly.
    13.2. Repeat steps 5 through 9.
    13.3. If the brake pedal moves slightly, replace the check valve and the hose.
    13.4. If the brake pedal does not move slightly, replace the booster assembly. Refer to Power Vacuum Brake Booster Replacement .
  16. Release the brake pedal.
  17. Let the engine run for 15 seconds.
  18. Without pressing the brake pedal, turn the ignition switch to LOCK.
  19. Press the brake pedal several times slowly.
  20. Inspect the brake pedal travel.
  21. If the brake pedal travel decreases with each brake pedal press, the booster is airtight. The booster is functioning normally.
  22. If the brake pedal press does not decrease in travel with each press, complete the following procedures:
  23. 20.1. Install a check valve and hose that are known to be operating properly.
    20.2. Repeat steps 10 through 13.
    20.3. If the brake pedal decreases with each brake pedal press, replace the check valve and hose.
    20.4. If the brake pedal press does not decrease in travel, replace the booster assembly. Refer to Power Vacuum Brake Booster Replacement .