Engine Cooling Flow Diagram - Hot Climate Markets

Courtesy of JAGUAR LAND ROVER NORTH AMERICA, LLC

When the engine is running, the coolant is circulated around the engine cooling system by the coolant pump. From the coolant pump, coolant flows through the cylinder heads and the engine oil cooler into the cylinder block and the heater manifold.

In the cylinder block, the coolant flows forward to the outlet tube. When the coolant is cold the thermostat is closed, coolant flows direct from the outlet tube back to the coolant pump. When the coolant reaches operating temperature, the thermostat begins to open to control the system temperature, coolant flows from the outlet tube to the coolant pump through the radiator and, if equipped, the auxiliary radiator. When the thermostat is open, the coolant flow through the radiator(s) also generates a coolant flow through the transmission fluid cooler.

From the heater manifold the coolant flows through the electronic throttle and the heater core, in parallel circuits that are unaffected by the position of the thermostat. From the electronic throttle, the coolant merges with bleed coolant from the coolant pump and the outlet tube and flows to the expansion tank. From the heater core, the coolant flows back to the inlet of the coolant pump.

Expansion and contraction of the coolant is accommodated by an air space in the expansion tank and the compliance of the flexible hoses.

When the coolant level in the coolant expansion tank is sufficient, the magnetic float is in the top position. In this position the magnetic field closes the switch contacts in the coolant level sensor. When the coolant level drops significantly below the MIN cold fill coolant level, the magnetic float descends, thus the switch contacts disconnected. The open circuit is sensed by the Body Control Module/Gateway Module (BCM/GWM), which sends a signal to the Instrument Cluster (IC) to display the "Coolant Level Low" warning message. The message is sent on the High Speed (HS) Controller Area Network (CAN) comfort systems bus.

For additional information, refer to: INSTRUMENT CLUSTER (G1890418) .

The cooling fan is operated by a fan control module integrated into the cooling fan motor. The fan control module regulates the voltage, and thus speed, of the cooling fan motor in response to a PWM  signal from the ECM. The cooling fan motor also provides a diagnostic feedback to the ECM through the PWM  connection.

The electric cooling fan receives a battery feed and an ignition feed from the engine junction box (EJB). The ignition feed is supplied from the ignition relay in the EJB, which is controlled by the ECM.

The ECM  calculates the required fan speed from the engine temperature, air conditioning (A/C) system pressure and automatic transmission fluid temperature. Under hot operating conditions, the fan may continue to operate for 4 minutes after the engine has been switched off.

The supercharger cooling system also uses the engine cooling system for charge air cooling.