The Engine Coolant Temperature (ECT) sensor resistance changes in response to engine coolant temperature. The sensor resistance decreases as the coolant temperature increases, and increases as the coolant temperature decreases. This provides a reference signal to the PCM, which indicates engine coolant temperature. The signal sent to the PCM by the ECT sensor helps the PCM to determine spark advance, EGR flow rate, air/fuel ratio, and engine temperature. The ECT also is used for temperature gauge operation by sending it's signal to the instrument cluster.
The ECT is a two wire sensor, a 5-volt reference signal is sent to the sensor and the signal return is based upon the change in the measured resistance due to temperature.
See Figures 1 through 5
- 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.
REMOVAL & INSTALLATION
See Figures 6 through 20
- Disconnect the negative battery cable.
- Drain and recycle the engine coolant.
- On the 2.0L engine, remove the air intake resonators.
- On the 2.5L engine, raise and support the vehicle.
- Disconnect the ECT sensor connector.
- Remove the ECT sensor from the thermostat housing (2.0L) or the water crossover tube (2.5L).
- Coat the sensor threads with Teflon® sealant.
- Thread the sensor into position and tighten to 10-14 ft lbs. (14-19 Nm) on the 2.5L engine and 89-120 inch lbs. (10-14 Nm) on the 2.0L engine.
- Attach the ECT sensor connector.
- On the 2.0L engine, install the air intake resonators.
- On the 2.5L engine, lower the vehicle.
- Connect the negative battery cable.
- Refill the engine cooling system.
- Start the engine and check for coolant leaks.
- Bleed the cooling system.