GM Service Manual Online
For 1990-2009 cars only

Tools Required

J 28662 Brake Pedal Effort Gauge

  1. DO NOT depress the brake pedal.
  2. Start the engine. Run the engine for 15 seconds.
  3. Using the J 28662 depress the brake pedal with a force of 294 N (66 lb).
  4. Turn the ignition switch to the LOCK position.
  5. If the brake pedal does not move slightly to the floor, the brake booster is airtight.
  6. If the brake pedal moves slightly to the floor, perform the following procedure:
  7. 6.1. Install an operable check valve and a vacuum brake booster hose. Refer to Vacuum Brake Booster Hose Replacement .
    6.2. DO NOT depress the brake pedal.
    6.3. Start the engine. Run the engine for 15 seconds.
    6.4. Using the J 28662 depress the brake pedal using a force of 294 N (66 lb).
    6.5. Turn the ignition switch to the LOCK position.
    6.6. If the brake pedal does not move slightly to the floor, the brake booster is airtight.
    6.7. If the brake pedal moves slightly to the floor, replace the brake booster. Refer to Power Vacuum Brake Booster Replacement .
  8. Release the brake pedal.
  9. Start the engine. Run the engine for 15 seconds.
  10. Turn the ignition switch to the LOCK position.
  11. Depress the brake pedal slowly 4 times.
  12. If the brake pedal travel decreases with each brake pedal press, the brake booster is airtight.
  13. If the brake pedal travel does not decrease with each press, perform the following procedure:
  14. 12.1. Install an operable check valve and a vacuum brake booster hose. Refer to Vacuum Brake Booster Hose Replacement .
    12.2. DO NOT depress the brake pedal.
    12.3. Start the engine. Run the engine for 15 seconds.
    12.4. Turn the ignition switch to the LOCK position.
    12.5. Depress the brake pedal slowly 4 times.
    12.6. If the brake pedal travel decreases with each brake pedal press, the brake booster is airtight.
    12.7. If the brake pedal travel does not decrease, replace the brake booster. Refer to Power Vacuum Brake Booster Replacement .
  15. Release the brake pedal.
  16. Start the engine. Run the engine for 15 seconds.
  17. Turn the ignition switch to the LOCK position.
  18. Pump the brake pedal until all of the vacuum reserve is exhausted from the brake booster.
  19. Using the J 28662 depress the brake pedal using a force of 294 N (66 lb).
  20. Start the engine.
  21. If the brake pedal moves slightly to the floor, a reserve brake pedal distance is present. The brake booster is functioning normally.
  22. If the brake pedal does not move slightly to the floor, perform the following steps:
  23. 20.1. Install an operable check valve and a vacuum brake booster hose. Refer to Vacuum Brake Booster Hose Replacement .
    20.2. DO NOT depress the brake pedal.
    20.3. Start the engine. Run the engine for 15 seconds.
    20.4. Turn the ignition switch to the LOCK position.
    20.5. Pump the brake pedal until all of the vacuum reserve is exhausted from the brake booster.
    20.6. Using the J 28662 depress the brake pedal using a force of 294 N (66 lb).
    20.7. Start the engine.
    20.8. If the brake pedal moves slightly to the floor, a reserve brake pedal distance is present. The brake booster is functioning normally.
    20.9. If the brake pedal does not move slightly to the floor, replace the brake booster. Refer to Power Vacuum Brake Booster Replacement .