Prizm L4-108 1.8L DOHC VIN 8 MFI (1995)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
DESCRIPTION
The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor whose resistance changes as a function of temperature) and is mounted
in the engine coolant stream. The ECT sensor is a "two-wire" sensor with a reference voltage and a ground provided by the PCM. Low coolant
temperature produces a high resistance and high temperatures result in a low resistance.
OPERATION
The PCM supplies a five-volt signal to the coolant sensor through a resistor in the PCM and measures the signal voltage. The voltage will be high
when the engine is cold and low when the engine is hot.
The ECT sensor provides engine coolant temperature information to the PCM for fuel enrichment, ignition timing, air management, idle speed
control and closed loop fuel control.
SENSOR CIRCUIT FAILURE
A failure in the ECT sensor circuit should set a DTC 22 Engine Coolant Temperature Sensor Circuit.
