Coolant Line/Hose: Description and Operation

This cooling system operates in three steps depending on the temperature of the engine coolant flowing through the cooling circuit.

^ 1st step With thermostat closed
At the engine coolant temperature of below 76°C (169°F) , the thermostat remains closed and the engine coolant flows through the bypass and heater circuits.
This permits the engine to warm up quickly.

^ 2nd step With thermostat opened
When the engine coolant temperature is above 76 - 80°C (169 - 176°F) , the thermostat opens and the engine coolant flows through the radiator where it is cooled.

^ 3rd step With radiator fan operating
When the engine coolant temperature rises above 95°C (203°F) , the ECM sends ON signal to the radiator fan in response to signal from the engine coolant temperature sensor and the radiator fan rotates.