What does it indicate if the Brakes On light illuminates and does not extinguish?

When the Brakes On light illuminates and does not extinguish, it indicates that there is a failure associated with the EP brake mechanism, leading to it not releasing properly. This is crucial to understand because the EP brake is responsible for controlling the train's speed and ensuring that it can stop safely.

If the light remains on, it informs the operator that the braking system is engaged, meaning that the train cannot proceed safely, as the brakes are not functioning correctly. This clear indication helps in diagnosing issues with the braking system before attempting to move the train, thereby preventing accidents and ensuring safety protocols are followed.

The other scenarios, such as the parking brake being engaged or the EP brake successfully releasing, would not result in the light staying illuminated. These options suggest that the train should be in a different operational state, one that does not correspond with the light being on continuously. Therefore, the illumination of the Brakes On light serves as a critical warning regarding the status of the EP brake, highlighting the need for immediate attention.