When making initial movement of a distributed power train after linking, what is the first action that must be taken?

When making the initial movement of a distributed power train after linking, ensuring that the SAME/OPPOSITE switch is in the proper position is a crucial first step. This switch controls the configuration of the distributed power system, which allows for coordinated operation between the lead and remote locomotive units. If this switch is not in the correct position, it can lead to improper communication between the locomotives, potentially causing significant operational issues or safety hazards during the train's initial movement.

By confirming the switch's position, the crew ensures that the distributed power system can effectively manage braking and acceleration, thereby enhancing the train's overall handling and safety. The other steps, such as ensuring the train is fully loaded or notifying the dispatch center, may also be important, but they do not take precedence over properly configuring the power system before any movement occurs.