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

Engine Coolant Temperature Sensor:

PURPOSE
The Coolant Temperature Sensor (CTS) is used to control:

^ Fuel delivery
^ Torque Converter Clutch (TCC)
^ Engine Spark Timing (EST)
^ Controlled Canister Purge (CCP)
^ Idle Air Control (IAC)
^ Cooling Fan

OPERATION:
The CTS is a thermistor that is located in the engine coolant flow. When the coolant temperature is low, the sensor produces a high resistance. When the coolant temperature is high, the sensor produces a low resistance.

The ECM sends a 5.0 volt signal to the CTS through a resistor in the computer and measures the voltage. The voltage will be high or low depending on coolant temperature. With the CTS varying its resistance, the ECM can sense engine coolant temperature by reading the varying voltage.

LOCATION:
Engine thermostat and coolant outlet.