What is the first step when performing a hydraulic brake check for a school bus?

When performing a hydraulic brake check for a school bus, the first step is to pump the brake pedal three times. This action helps ensure that the brake system is functioning properly and establishes the brake pedal's normal operating position. By pumping the brake pedal, the driver can build up hydraulic pressure in the brake lines, which is crucial for checking the feel and response of the brakes. If there is any sponginess or unusual feel in the pedal after pumping, this could indicate issues such as air in the system or a leak that requires further investigation.

Starting the engine, while an important part of the overall vehicle safety checks, is not the initial step in the brake check process. Checking the brake fluid level and inspecting the brake lines visually are also valuable safety practices, but these steps typically follow the initial pumping of the brake pedal, helping to further assess the health of the brake system after establishing its operational status.