What does it indicate if the release light does not light with the master controller in coast position?

The situation where the release light does not illuminate while the master controller is in the coast position indicates a potential local brake problem. The release light is designed to come on when the brakes are fully released, and its failure to light suggests that there may be an issue preventing the brakes from releasing properly.

If the brakes were functioning correctly and adequately released, the release light would signal that status. Therefore, the absence of this signal raises concern about either the brake mechanism or the associated electrical system that powers the light. This condition warrants further investigation to ensure the safety and operational readiness of the train.