What should the driver do before performing a low air pressure check?

Before performing a low air pressure check, it is essential for the driver to release the parking brake. This step is crucial because the parking brake engages the vehicle's braking system, which can affect the air pressure readings. Without releasing the parking brake, the vehicle remains immobilized, and air pressure might not be able to flow or equalize properly throughout the system. This process ensures that the driver can accurately assess whether the air pressure is at an acceptable level for safe operation of the vehicle.

While turning the master switch off, activating hazard lights, and engaging the engine brake might be part of other pre-trip procedures or safety measures, they do not directly relate to the accurate assessment of low air pressure in this context. Engaging in these actions would not provide the necessary conditions for a proper low air pressure check, making them less relevant in this specific scenario.