Which of the following is the last step before starting an automated transmission-serviced truck?

In the context of preparing an automated transmission-serviced truck for operation, the final step is typically to ensure that the Engine Control Unit (ECU) is correctly calibrated and programmed to handle the specific parameters of the vehicle and its transmission system. Reprogramming the ECU can involve updating software or ensuring that the settings match the specifications required by the vehicle's automated transmission, which is crucial for its proper function.

Setting the park brake and verifying the shift control panel lights are important steps in ensuring the vehicle's safety and readiness, but they are generally performed throughout the servicing and preparation process rather than being the conclusive step. Likewise, clearing fault codes might be necessary before starting the vehicle to ensure that any existing issues are addressed, but it doesn’t encompass the finalization of the vehicle's operational readiness in terms of the transmission system.

Thus, ensuring the ECU is properly programmed and reprogrammed as needed is critical to the optimal functioning of the automated transmission, making it the final necessary step before the truck can be started safely and effectively.