Coolant Temperature Sensor/Switch (For Computer): Testing and Inspection

ENGINE COOLANT TEMPERATURE SENSOR (ECTS)

INSPECTION

FUNCTION AND OPERATION PRINCIPLE




Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant
passage of the cylinder head for detecting the engine coolant temperature. The ECTS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the ECTS decreases as the temperature increases, and increases as the temperature decreases. The reference 5 V in the PCM is supplied to the ECTS via a resistor in the PCM.That is, the resistor in the PCM and the thermistor in the ECTS are connected in series. When the resistance value of the thermistor in the ECTS changes according to the engine coolant temperature, the output voltage also changes. During cold engine operation the PCM increases the fuel injection duration and controls the ignition timing using the information of engine coolant temperature to avoid engine stalling and improve driveablity.

Specification:

SPECIFICATION

Circuit Diagram:

CIRCUIT DIAGRAM

COMPONENT INSPECTION
1. Turn ignition switch OFF.
2. Disconnect ECTS connector.
3. Remove the ECTS.




4. After immersing the thermistor of the sensor into engine coolant, measure resistance between ECTS terminals 1 and 3.
5. Check that the resistance is within the specification.

Specification: Refer to SPECIFICATION.