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

ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION

Inspection of Resistance

NOTE: Perform the following test only when directed.

1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.) (See ENGINE COOLANT REPLACEMENT.)
2. Disconnect the ECT sensor connector.




3. Remove the ECT sensor.




4. Place the sensor in water with a thermometer, and heat the water gradually.

Specification:

5. Measure the resistance between the ECT sensor terminals using an ohmmeter.
- If not as specified, replace the ECT sensor.
- If ECT sensor is okay, but PID value is out of specification, perform the "Circuit Open/Short Inspection".

6. Reconnect the ECT sensor connector.

Circuit Open/Short Inspection

Open circuit




- If there is no continuity, the circuit is open. Repair or replace the harness.
- Reference voltage circuit (ECT sensor connector terminal A and PCM connector terminal 4P through common connector.)
- GND circuit (ECT sensor connector terminal B and PCM connector terminal 4O through common connector.)

Short circuit
- If there is continuity, the circuit is shorted. Repair or replace the harness.
- ECT sensor connector terminal A and PCM connector terminal 4P through common connector to GND.

Water Temperature Sender Unit Inspection

1. Drain the engine coolant. (See COOLING SYSTEM SERVICE WARNINGS.) (See ENGINE COOLANT REPLACEMENT.)
2. Remove the ECT sensor.
3. Place the sensor in water with a thermometer, and heat the water gradually.

Specification:

4. Measure the resistance between ECT sensor terminal C and body GND using an ohmmeter.
- If not as specified, replace the ECT sensor.