Auxiliary Heater: General

Auxiliary heating is provided by a FFBH, which boosts the temperature of the coolant supplied to the heater from the engine. Fuel for the FFBH is taken from the vehicle fuel tank, through a fuel line attached to the fuel pump module. An auxiliary fuel pump supplies the fuel at low pressure to the FFBH. In the FFBH, the fuel is burned and the resultant heat output is used to heat the engine coolant.

Operation of the FFBH is enabled and disabled by the automatic temperature control (ATC) module.