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TESTING

Fig. 1: Unplug the ECT sensor electrical connector

Fig. 2: Test the resistance of the ECT sensor across the two sensor pins

Fig. 3: Another method of testing the ECT is to submerge it in cold or hot water and check resistance

Fig. 4: The ECT can be monitored with an appropriate and Data-stream capable scan tool

  1. Drain the engine coolant to a level below the intake manifold.
  2. Disconnect the sensor wiring harness and remove the coolant temperature sensor from the engine.
  3. Place the temperature sensing portion of the sensor into a pan of hot water. Use a thermometer to monitor the water temperature.
  4. Measure the resistance across the sensor terminals while the sensor is in the water. Compare obtained reading to specifications:
    1. Water temperature of 32°F (0°C) — 5.1–6.5 kilo-ohms present
    2. Water temperature of 68°F (20°C) — 2.1–2.7 kilo-ohms present
    3. Water temperature of 104°F (40°C) — 0.9–1.3 kilo-ohms present
    4. Water temperature of 176°F (80°C) — 0.26–0.36 kilo-ohms present
  5. If the resistance differs greatly from standard value, replace the sensor.

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