Nissan Sentra/Pulsar/NX 1982-1996 Repair Guide

Coolant Temperature (ECT) Sensor

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OPERATION



The ECT sensor is a temperature-sensitive resistor that monitors the coolant temperature. The sensor is threaded into a coolant passage. As the coolant heats from the engine use, the resistance of thermistor inside the ECT sensor decreases. The resistance change, causes the sensor reference line voltage to drop in proportion with the resistance change. The ECM detects the temperature change and adjusts the air/fuel mixture to compensate for the change.

TESTING



See Figures 1, 2, 3, 4, 5 and 6



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Fig. Fig. 1: Coolant temperature sensor specifications chart-E15ET engine



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Fig. Fig. 2: Coolant temperature sensor specifications-all 1987-90 engines



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Fig. Fig. 3: Coolant temperature sensor specifications chart-1991-94 GA16DE engine



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Fig. Fig. 4: Coolant temperature sensor specifications chart-1991-94 SR20DE engine

  1. Disconnect the ECT sensor connector.
  2.  
  3. Place a known, accurate thermometer in water to verify temperature.
  4.  
  5. Place the ECT sensor in water and heat the water while measuring resistance.
  6.  
  7. Compare resistance with the appropriate specifications chart.
  8.  
  9. Replace the ECT sensor if the resistance readings are not within specifications.
  10.  

REMOVAL & INSTALLATION



  1. Drain the engine coolant.
  2.  
  3. Remove harness connector.
  4.  
  5. Using the correct size wrench, remove the ECT sensor.
  6.  

To install:
  1. Coat the threads of the new ECT sensor with an approved sealing compound.
  2.  
  3. Install the new ECT sensor using the correct size wrench.
  4.  
  5. Reconnect ECT harness connector to the new ECT sensor.
  6.  



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Fig. Fig. 5: Coolant temperature sensor specifications chart-1995-96 GA16DE and SR20DE engines



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Fig. Fig. 6: Coolant temperature sensor resistance graph-1995-96 GA16DE and SR20DE engines

  1. Refill the engine coolant.
  2.  
  3. Run the engine until the cooling fans operate and check for leaks.
  4.  

 
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