Cooling System: Description and Operation

Cooling System Description and Operation

This vehicle is equipped with three fully independent cooling systems. The power electronics cooling system is dedicated to cooling the battery charger and the power inverter module. The battery cooling system is dedicated to cooling and heating the high voltage battery. The engine cooling system is dedicated to cooling the engine and providing heat to the passenger compartment.

Engine Cooling System Description and Operation

The engine cooling system consists of a radiator, two 12 volt pulse width modulated (PWM) radiator fans, a 12 volt coolant pump, a coolant flow control valve, a high voltage heater and a heater core.





The hybrid/EV powertrain control module 2 controls the radiator cooling fans. The cooling fans are controlled with a Pulse Width Modulated (PWM) signal. The hybrid/EV powertrain control module 2 diagnoses any faults with the hardwire circuit to the engine control module. The engine control module sends a fan request PWM signal to the hybrid/EV powertrain control module 2 through a hardwire circuit. The hybrid/EV powertrain control module 2 operates in a pass-through mode for the engine control module fan request. The higher the duty cycle the higher the cooling fan speed.

The hybrid/EV powertrain control module 2 sends a request to the engine control module for the cooling fans to be turned on. The engine control module uses this request and other vehicle inputs to decide if and what speed the cooling fans should operate. The engine control module sends the cooling fan command to the hybrid/EV powertrain control module 2. The hybrid/EV powertrain control module 2 sends the signal to the cooling fans to operate and at what speed.

If the vehicle is in Charge Mode and the hybrid/EV powertrain control module 2 requests the cooling fans to operate, if the engine control module is not awake, the hybrid/EV powertrain control module 2 will control the cooling fans. If active cooling is needed, the engine control module wakes up to operate the air conditioning control module and then the engine control module is the master controller for the fans.





The HVAC Control Module turns on the coolant pump and monitors the temperature sensors in the passenger compartment, engine radiator, high voltage heater and the engine to determine the position of the coolant flow control valve and if the high voltage heater is needed. Passenger compartment heat is provided by air flowing through the heater core. The heater core is heated by coolant from either the engine or the high voltage heater.

The engine cooling system circulates a 50/50 mixture of DEX-COOL and distilled water.