Why should the Door Master Switch always be on during a pre-trip check?

The Door Master Switch should always be on during a pre-trip check to enable interlocking safety features. These safety features are critical for ensuring that the bus operates safely when doors are involved. Interlocking systems prevent the bus from being driven while the doors are open, thereby safeguarding passengers and ensuring that the bus is in a safe condition to operate. When the Door Master Switch is activated, it allows the driver to check the door mechanisms, ensuring they open and close correctly and are functioning properly before the bus goes into service. This procedure helps to prevent accidents and ensure the safety of both the driver and passengers.

The other options do not directly address the primary safety function that the Door Master Switch provides during a pre-trip check. For instance, while disabling passenger alarms, allowing the driver to exit easily, or keeping lights activated may have certain operational benefits, they do not contribute to the overarching safety protocols in the same way that the interlocking features do.