What action must the driver take if the trip fails to reset due to a fault?

When a trip fails to reset due to a fault, the appropriate action involves operating the trip cock bypass key switch. This action is specifically designed to allow the system to bypass the fault condition temporarily, enabling the driver to continue operations or to safely maneuver the vehicle until the issue can be addressed by maintenance.

The trip cock bypass key switch serves a critical function; it's a safety mechanism that permits operators to manage situations where a fault may prevent normal operation. Utilizing this bypass allows for operational flexibility while ensuring that the fault is logged for investigation and resolution.

In contrast, actions such as activating the emergency stop button or turning off the master key generally lead to a complete shutdown of the system, which is not a practical solution for a failed trip reset. Contacting maintenance, while important, does not provide any immediate remedy to the inability to reset the trip and could lead to extended downtime. Thus, using the trip cock bypass key switch is the most effective immediate response in this scenario.