Coolant Temperature Sensor/Switch (For Computer): Description and Operation

Coolant And Charge Temperature Sensors:

The coolant temperature sensor is installed in the thermostat housing where it maintains constant contact with the engine coolant. The engine controller sends out a reference voltage of approximately five (5) volts to the coolant temperature sensor. As coolant temperature changes, the internal resistance of the sensor will change, causing a voltage drop across the sensor. The engine controller reads the voltage drop across the sensor, and therefore the engine temperature, by the amount of voltage drop at the sensor. The sensor has an operating range of -40°F to 265°F.

Based on the amount of voltage drop at the coolant sensor, the engine controller will:

^ Adjust the fuel injector pulse width. A cold engine will receive a longer pulse width, allowing for a richer mixture.
^ Adjust the boost levels. A cold engine will receive slightly lower amounts of turbocharger boost.
^ Monitor and adjust engine warm-up speed.
^ Adjust ignition timing when the engine is cold.
^ Turn ON the engine cooling fan.