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

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

The engine coolant temperature sensor installed in the engine coolant passage of the cylinder head detects the engine coolant temperature and emits signals to the ECM. This part employs a thermistor which is sensitive to changes in temperature. The electric resistance of the thermistor decreases in response to a temperature rise. The ECM determines engine coolant temperature by the sensor output voltage and provides optimum fuel enrichment when the engine is cold.

Circuit Diagram:

Using Hi-Scan:

USING MULTI-METER
1. Remove engine coolant temperature sensor from the intake manifold.




2. With temperature sensing portion of engine coolant temperature sensor immersed in hot engine coolant, check resistance.
3. If the resistance deviates from the standard value greatly, replace the sensor.

Harness Inspection Procedure:

Troubleshooting Procedures:

Using Voltmeter:

INSTALLATION
1. Apply sealant LOCTITE 962T or equivalent to threaded portion.

2. Install engine coolant temperature sensor and tighten it to specified torque.

Tightening torque
Engine coolant temperature sensor: 20-40 Nm (200-400 kg.cm, 14-29 lb.ft)

3. Securely connect the harness connector.