See Figures 1 and 2
The engine coolant temperature sensor resistance changes in response to engine coolant temperature. The sensor resistance decreases as the coolant temperature increases. This provides a reference signal to the PCM, which indicates engine coolant temperature.
On 3.0L engines, the ECT is mounted at the top of the water outlet housing on the lower intake manifold. The second sensor (green) mounted to the lower intake manifold is the coolant temperature sender for the coolant gauge on the instrument panel.
On 3.8L engines, the ECT is mounted to the side of the water outlet housing on the lower intake manifold.
See Figures 3 and 4
- 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
- Partially drain the engine cooling system until the coolant level is below the ECT sensor mounting hole.
- Disconnect the negative battery cable.
- Disconnect the wiring harness from the ECT sensor.
- Remove the coolant temperature sensor from the intake manifold.
- Coat the sensor threads with Teflon® sealant.
- Thread the sensor into the intake manifold and tighten to 71-115 inch lbs. (8-13 Nm).
- Connect the negative battery cable.
- Refill the engine cooling system.
- Start the engine and check for coolant leaks. Top off the cooling system.