Diagnostic Aids
- Inspect the ECT sensor terminals for corrosion and for engine coolant leaking through the sensor. Engine coolant that is leaking through the sensor will create a high resistance short to ground. This condition results in less voltage on the ECT sensor signal circuit, which is interpreted by the ECM as a warmer ECT.
- This diagnostic runs in a specific range. Measure and record the resistance of the ECT sensor at various ambient temperatures greater than -8°C (+18°F), then compare those measurements to the Temperature vs Resistance table. Refer to Temperature Versus Resistance .
- An IAT sensor that is skewed colder at various ambient temperatures due to greater resistance than is normal will increase the range between these two sensors. Measure and record the resistance of the IAT sensor at various ambient temperatures, then compare those measurements to the Temperature vs Resistance table. Refer to Temperature Versus Resistance .
- A slight to moderate resistance in the IAT sensor signal circuit or low reference circuit will increase the range between these two sensors. This condition results in a greater voltage on the IAT sensor signal circuit, which is interpreted by the ECM as a colder IAT.