What is the first step in a proper air brake system check?

Starting the engine and building air pressure is essential as the first step in a proper air brake system check. When you start the engine, the air compressor begins to operate, building up the necessary air pressure in the system to ensure that the brakes can function effectively. Without adequate air pressure, you cannot accurately assess the performance of the air brakes, including the operation of components such as the air dryer, governor, and valves.

Once the air pressure is built, you can then perform further checks, such as testing for leaks and verifying that the pressure gauge readings are within the acceptable range. This foundational step is critical because air brake systems rely on compressed air to apply and release the brakes, so ensuring that you have sufficient pressure is a prerequisite for any subsequent inspection or testing.

Additionally, while checking tire pressure, inspecting the brake fluid level, and conducting a visual inspection are all important aspects of vehicle maintenance and safety, they do not directly pertain to the functionality of the air brake system itself in the same way that establishing proper air pressure does.