Where is the engine coolant heater located in 2002 excursion diesel?

The engine coolant heater in a 2002 Ford Excursion diesel is located in the engine block itself. It's not a separate, easily visible unit like a block heater on some gasoline engines. It's integrated within the engine's cooling system. You won't see it externally; it's an internal component. The cord for the heater will plug into the vehicle somewhere near the front of the engine compartment, often near the radiator.