A: To perform an operating check on the brake system, start by depressing the brake pedal multiple times with the engine off to ensure there is no change in the pedal reserve distance. Then, depress the pedal and start the engine, checking for a slight downward movement of the pedal, which indicates normal operation. For an airtightness check, start the engine and turn it off after a minute or two. Slowly depress the brake pedal several times, noting if it goes down further on the first depression but gradually rises on subsequent depressions, indicating an airtight booster. To install the booster, place it into position and tighten the retaining bolts to the specified torque. Connect the pushrod to the brake pedal and install the clip. Install the master cylinder and reconnect the vacuum hose. For ABS-equipped models, reposition the hydraulic control unit and secure it with mounting nuts.