The engine coolant temperature sensor resistance changes in response to engine coolant temperature. The sensor resistance decreases as the surrounding temperature increases. This provides a reference signal to the PCM, which indicates engine coolant temperature.
See Figures 1, 2 and 3
- Disengage the engine wiring harness connector from the ECT sensor.
- Connect an ohmmeter between the ECT sensor terminals, and set the ohmmeter scale on 200,000 ohms.
- With the engine cold and the ignition switch in the OFF position, measure and note the ECT sensor resistance. Attach the engine wiring harness connector to the sensor.
- Start the engine and allow it to warm up to normal operating temperature.
- Once the engine has reached normal operating temperature, turn it OFF .
- Once again, detach the engine wiring harness connector from the ECT sensor.
- Measure and note the ECT sensor resistance, then compare the cold and hot ECT sensor resistance measurements with the accompanying chart.
- Replace the ECT sensor if the readings do not approximate those in the chart; otherwise, reattach the engine wiring harness connector to the sensor.
REMOVAL & INSTALLATION
See Figures 4 through 8
- Partially drain the engine cooling system until the coolant level is below the ECT sensor mounting hole.
- Disconnect the negative battery cable.
- Detach the wiring harness connector from the ECT sensor.
- Using an open-end wrench, remove the coolant temperature sensor from the intake manifold.
Thread the sensor into the intake manifold by hand, then tighten it to the following values:
3.8L engine-124-168 inch lbs. (14-19 Nm)
- Reattach the wiring harness connector to the ECT sensor.
- Connect the negative battery cable.
- Refill the engine cooling system.
- Start the engine, check for coolant leaks and top off the cooling system.