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.
The ECT sensor is mounted on the lower intake manifold near the water outlet/thermostat housing, or on the water outlet/thermostat housing itself.
See Figures 1 and 2
- 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 the engine to warm up to normal operating temperature.
- Once the engine has reached normal operating temperature, turn the engine 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 Figure 3
- 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 or thermostat housing.
- Thread the sensor into the intake manifold, or thermostat housing, by hand, then tighten it securely.
- Connect the negative battery cable.
- Refill the engine cooling system.
- Start the engine, check for coolant leaks and top off the cooling system.