Leak Test
- Depress brake pedal with engine running. Turn ignition off. If pedal height does not vary while depressed for 30 seconds, vacuum booster is okay. If pedal rises, vacuum booster leaks.
- With engine stopped, depress brake pedal several times using normal pressure. Pedal should be low when first depressed. On consecutive applications, pedal height should gradually rise. If pedal height does not vary, check power brake booster check valve.