Grand AM L4-138 2.3L DOHC VIN D MFI (1994)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor
PURPOSE
The Engine Coolant Temperature (ECT) Sensor is used to control:
^
Fuel delivery
^
Engine Spark Timing (IC)
^
Idle Air Control (IAC)
^
Cooling Fan
^
Controlled Canister Purge (CCP)
^
Torque Converter Clutch (TCC)
LOCATION
Engine thermostat and coolant outlet.
OPERATION
The ECT sensor 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 PCM sends a 5.0 volt signal to the ECT sensor 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.
