Brake Booster Operation Check

Start the engine and let it run for one or two minutes, then stop it. If the pedal depresses fully the first time but gradually rises higher on subsequent presses, the booster is operating properly. If the pedal height remains unchanged, the booster is not operating properly.

With the engine stopped, depress the brake pedal several times. Then depress the brake pedal and start the engine. If the pedal moves down slightly, the booster is in good condition. If there is no change, the booster is not operating properly.

With the engine running, depress the brake pedal and stop the engine. Hold the pedal depressed for 30 seconds. If the pedal height does not change, the booster is good. If the pedal rises, the booster is not operating properly. If the above three tests are all satisfactory, the booster performance can be judged as good. Even if one of the above three tests is not satisfactory, inspect the check valve, vacuum hose and booster for malfunction.