Grand AM L4-138 2.3L VIN A MFI (1992)
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/PCM 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. By varying the voltage the computer will sense engine coolant temperature.
LOCATION
Engine thermostat and coolant outlet.
