There are a few items you should check before beginning more extensive testing.
Sensor Installed In Vehicle
- Disconnect the engine wiring harness from the ECT sensor.
- Connect an ohmmeter between the ECT sensor terminals.
- With the engine cold and the ignition switch in the OFF position, measure and note the ECT sensor resistance.
- Connect the engine wiring harness to the sensor.
- Start the engine and allow the engine to reach normal operating temperature.
- Once the engine has reached normal operating temperature, turn the engine OFF .
- Once again, disconnect the engine wiring harness from the ECT sensor.
- Measure and note the ECT sensor resistance with the engine hot.
- Compare the cold and hot ECT sensor resistance measurements with the accompanying chart.
- If readings do not approximate those in the chart, the sensor may be faulty.
Sensor Removed From Vehicle
- Remove the ECT sensor from the vehicle.
- Immerse the tip of the sensor in a container of water.
- Connect a digital ohmmeter to the two terminal of the sensor.
- Using a calibrated thermometer, compare the resistance of the sensor to the temperature of the water. Refer to the accompanying resistance value chart.
- Repeat the test at two other temperature points, heating or cooling the water as necessary.
- If the sensor does not meet specifications, it must be replaced.