Brake Booster Operating Test

WARNING: This page is about a different car, the 2011 Hyundai Tucson. However, it is still accessible from the selected car via links, so may be relevant.

For simple checking of the brake booster operation, carry out the following tests.

Run the engine for one or two minutes, and then stop it. If the pedal depresses fully the first time but gradually becomes higher when depressed succeeding times, the booster is operating properly, if the pedal height remains unchanged, the booster is inoperative.

Fig 1: Identifying Proper And Improper Condition Of Pedal Depresses
Courtesy of HYUNDAI MOTOR CO.
With the engine stopped, step on the brake pedal several times.
Then step on the brake pedal and start the engine. If the pedal moves downward slightly, the booster is in good condition. If there is no change, the booster is inoperative.

Fig 2: Identifying Proper And Improper Condition Of Pedal Depresses (Engine Stopped Or Started)
Courtesy of HYUNDAI MOTOR CO.
With the engine running, step on the brake pedal and then stop the engine. Hold the pedal depressed for 30 seconds. If the pedal height does not change, the booster is in good condition, if the pedal rises, the booster is inoperative.
If the above three tests are okay, the booster performance can be determined as good.

Even if one of the above three tests is not okay, check the check valve, vacuum hose and booster for malfunction.

Fig 3: Identifying Proper And Improper Condition Of Pedal Depresses
Courtesy of HYUNDAI MOTOR CO.