Leak Test
- Press brake pedal with engine running. Turn ignition off. If pedal height does not change while pressed for 30 seconds, vacuum booster is okay. If pedal rises, vacuum booster is leaking.
- With engine stopped, press brake pedal several times with normal pressure. Pedal should be low when first pressed. On consecutive applications, pedal height should gradually increase. If pedal height does not change, check power brake booster check valve.