Engine Coolant Temperature (ECT) Sensor
WARNING: This page is about a different variant/trim than selected.
If an ECT sensor-related code is present, perform appropriate DTC test. See TESTS W/CODES - 7.4L article. An out-of-calibration sensor may not set a trouble code. Use following procedure to test sensor calibration. Disconnect ECT sensor harness connector. Measure resistance between ECT sensor terminals. Sensor resistance should be as specified. See ECT SENSOR RESISTANCE VALUES table. Resistance should be high when engine is cold and drop as engine warms. With vehicle sitting overnight, IAT sensor and coolant sensor should have close to the same resistance reading.
ECT SENSOR RESISTANCE VALUES
| Temperature °F (°C) | Ohms |
|---|---|
| 212 (100) | 177 |
| 158 (70) | 467 |
| 104 (40) | 1459 |
| 68 (20) | 3520 |
| 32 (0) | 9420 |
| 5 (-15) | 21,450 |
| -40 (-40) | 100,700 |
NOTE:
Intake Air Temperature (IAT) sensor may also be referred to as Manifold Air Temperature (MAT) sensor.