A method of controlling a fluid heater control system for a locomotive, the fluid heater control system including a heater assembly including a water pump and a heating element, the method including determining if a fuel pump of the locomotive is on, if the fuel pump is off, activating the heater assembly, running the water pump for a first predetermined period of time, determining if a temperature of the fluid is greater than a first predetermined threshold, and if the temperature of the fluid is greater than the first predetermined threshold, deactivating the water pump for a second predetermined time period.