What test must an engineer perform if they change the train type selector?

When an engineer changes the train type selector, it is essential to perform an Automatic Cab Signal & Enforcement System (ACSES) self-test to ensure that the system is functioning properly and that it is calibrated to the new train type. This self-test confirms that the equipment is set up correctly to provide the necessary signals and enforcement commands relevant to the specific type of train being operated.

Conducting the ACSES self-test verifies the compatibility and readiness of all electronic systems that interact with the train's operational characteristics. This step is crucial for safety reasons, ensuring that the train adheres to the speed limits, signals, and other critical functionalities according to the specifications of the new type selected.

While other options such as initiating a brake test or checking fuel levels are important procedures in overall train maintenance and operation, the specific action required after changing the train type selector is to check the ACSES system to guarantee the operational integrity of the train as configured. Inspecting the train's interior is also not directly related to the changes made with the train type selector and does not address the immediate need for system verification that the ACSES self-test fulfills.