The ECT is a thermistor (a resistor which changes valve based on the temperature it encounters) that is mounted near the thermostat housing on the engine. Low temperatures create high resistance in the sensor, while high temperatures will produce low resistance. Coolant temperature is an important parameter and will affect most calculations made by the ECM.
See Figure 1
- Disconnect the sensor electrical harness.
- Measure resistance between the sensor terminals.
- Resistance should be high when the engine is cold and steadily drop as the engine warms.
- If resistance does not drop steadily or resistance values do not match those in the coolant temperature resistance chart, the sensor is faulty.
- If resistance is within specification, check power and ground circuits.
REMOVAL & INSTALLATION
See Figures 2 and 3
- Disconnect the negative battery cable.
- Drain the engine coolant.
- Label and disconnect the sensor electrical harness
- Carefully remove the sensor.
- Coat the sensor threads with Teflon® sealant.
- Carefully install the sensor and tighten to 14-29 ft. lbs. (20-40 Nm) on all engines except 1.5 (VIN K), 1.8L (VIN M) and 2.0L (VIN F). Tighten 1.5 (VIN K), 1.8L (VIN M) and 2.0L (VIN F) sensors to 11-15 ft. lbs. (15-20 Nm).
- Connect the sensor electrical harness
- Fill the engine with coolant.
- Connect the negative battery cable.