Cooling System: Description and Operation

How the Circuit Works

Battery voltage is provided at all times to the radiator fan relay contacts through 11 and to the A/C condenser fan relay contacts through 9. With the ignition switch in ON (II), battery voltage is supplied to the A/C condenser fan relay coil. The PCM controls power to the radiator fan relay coil. The PCM uses input from the ECT sensors and the A/C pressure sensor to control the fans.

In normal operating coolant temperature conditions, the PCM grounds the A/C condenser fan relay coil. Battery voltage is provided to the A/C condenser fan motor and the radiator fan motor in series through 9.

In extremely high coolant temperature conditions, the PCM grounds the A/C condenser fan relay coil and the radiator fan relay coil. Battery voltage is provided to the A/C condenser fan motor through 9 and to the radiator fan motor through 11.

In both cases, the fans will run until ground is removed from the relay coil(s).

With the engine in Auto-Stop Mode, the electric water pump is operated to circulate the coolant. The electric water pump is controlled by the ECT sensors.