Fuel Heater: Description and Operation

Fuel Heater And Temperature Sensor Location:

PURPOSE
The Fuel Heater is used to prevent diesel fuel from waxing during cold weather operation.

OPERATION
The heater assembly is equipped with a built-in sensor (thermostat) that senses fuel temperature. When the temperature is below 40° F, the built-in sensor allows current to flow to the built-in heater element warming the fuel. When the temperature is above 80° F, the sensor stops current flow to the heater element.

Voltage to operate the fuel heater is supplied from the ignition switch and through the Fuel Heater Relay.

The Fuel Heater and Fuel Heater Relay are not controlled by the Powertrain Control Module (PCM).

The built-in heater element operates on 12 volts, 300 watts at 0° F.

The fuel heater assembly also contains a pre-filter to prevent contaminants from entering the fuel transfer pump. A minimum of 7 volts is required to operate the fuel heater. The resistance value of the heater element is less than 1 ohm (cold) and up to 1000 ohms warm.