Leak Test

1. With engine running, depress brake pedal and hold, then stop engine. If pedal height does not vary with brake pedal depressed for 30 seconds, vacuum booster is operating. If pedal rises, booster is faulty.
2. Depress brake pedal several times with normal pressure. When pedal is first depressed, it should be low. As pedal is depressed, pedal height should gradually rise. If pedal height does not vary, check booster check valve.