Final answer:
If the motors on a car continue to take power when the master controller is in the OFF position, the train operator should check for a malfunction in the electrical system.
Step-by-step explanation:
If the motors on a car continue to take power when the master controller is in the OFF position, the train operator should check for a malfunction in the electrical system. This could be caused by a faulty switch or a short circuit. It is important to address this issue promptly to avoid unnecessary power consumption and potential damage to the car's electrical system.