S2000 L4-2.2L (2004)
Vacuum Brake Booster: Testing and Inspection
Brake Booster Test
Functional Test
1. With the engine stopped, press the brake pedal several times to deplete the vacuum reservoir, then press the brake pedal hard and hold it for 15
seconds. If the brake pedal sinks, either the master cylinder is bypassing internally, or the brake system (master cylinder, lines, modulator,
proportioning valve, or caliper) is leaking.
2. Start the engine with the brake pedal pressed. If the brake pedal sinks slightly, the vacuum booster is operating normally. If the brake pedal height
does not vary, the booster or check valve is faulty.
3. With the engine running, press the brake pedal lightly. If the brake pedal sinks more than 10 mm (3/8 inch) in 3 minutes, the master cylinder is
faulty.
Leak Test
1. Press the brake pedal with the engine running, then stop the engine. if the brake pedal height does not vary while pressed for 30 seconds, the
vacuum booster is OK. If the pedal rises, the booster is faulty.
2. Turn the ignition switch to lock (0) and wait 30 seconds, press the brake pedal several times using normal pressure. When the brake pedal is first
pressed, it should be low. On consecutive applications, the brake pedal height should gradually rise. If the brake pedal position does not vary,
check the booster check valve.
3. Disconnect the brake booster vacuum hose (check valve built-inch) (A) at the booster (B).
4. Start the engine, and let it idle. There should be vacuum available. If no vacuum is available, the check valve is not working properly. Replace the
brake booster vacuum hose and check valve, and retest.
5. Start the engine, and then pinch the brake booster vacuum hose between the check valve and the booster.
6. Turn the ignition switch to lock (0), and wait 30 seconds. Press the brake pedal several times using normal pressure. When the brake pedal is first
pressed, it should be low. On consecutive applications, the brake pedal height should gradually rise.
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If the pedal position does not vary, replace the brake booster.
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If the pedal position varies, replace the brake booster vacuum hose/check valve assembly.
