- Inspect the Engine Coolant Temperature (ECT) sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT.
- Check the condition of the connector. Make sure the connector is firmly attached. Check for broken or bent connector pins. Repair any connector damage before continuing with troubleshooting the issue.
Check the condition of the wiring to the connector. If the wiring is damaged, repair the wiring before continuing with any further tests.
NOTEThe sensor is threaded into the coolant passage in the back of the cylinder head.
- Unplug the connector from the sensor and use the chart to check the sensor resistance with an ohmmeter. This can also work if the sensor is removed and immersed in a container of water.
- Remove the coolant temperature sensor.
- Place the sensor in a container of water with a temperature approximately 20 degrees C (68 F).
- Using an ohmmeter, check resistance between the terminals. The resistance should be 3520 Ohms.
- Raise the temperature of the container of water to approximately 80 degrees C (176F).
- Using an ohmmeter, check resistance between the terminals. The resistance should be 332 Ohms.
If the resistance is not as specified, replace the sensor.