What precaution should be taken when leaving a locomotive unattended in temperatures below 32 degrees F?

When leaving a locomotive unattended in temperatures below 32 degrees Fahrenheit, it is crucial to place the Isolation switch in the Winter/Isolate position. This action helps to protect the locomotive's systems from potential damage due to freezing temperatures. By isolating the systems, it prevents any unnecessary power draw that could lead to overheating or other complications when the locomotive is not in operation.

Activating the heating system might seem like a good approach, but leaving the locomotive unattended does not guarantee that the heating system will function correctly without someone monitoring it. Similarly, leaving the throttle in Run 1 could cause the locomotive to stay active, leading to inefficient fuel use, increased wear, and potential safety hazards if it were to inadvertently move. Ensuring that the engine is turned off is a reasonable step, but if the Isolation switch is not in the Winter/Isolate position, there could still be risks associated with freezing temperatures affecting unprotected systems. Thus, utilizing the Isolation switch effectively mitigates these risks.