Toyota Celica 1994-1998 Repair Guide

Engine Coolant Temperature (ECT) Sensor

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OPERATION



The Engine Coolant Temperature (ECT) sensor's function is to advise the ECM of changes in engine temperature by monitoring the changes in coolant temperature. The sensor must be handled carefully during removal. It can be damaged (thereby affecting engine performance) by impact.

TESTING



See Figures 1 and 2

  1. Disconnect the engine wiring harness from the ECT sensor.
  2.  
  3. Connect an ohmmeter between the ECT sensor terminals.
  4.  



Click image to see an enlarged view

Fig. Fig. 1: Inspect the resistance between the terminals of the engine coolant temperature sensor

  1. With the engine cold and the ignition switch in the OFF position, measure and note the ECT sensor resistance.
  2.  
  3. Connect the engine wiring harness to the sensor.
  4.  
  5. Start the engine and allow the engine to reach normal operating temperature.
  6.  
  7. Once the engine has reached normal operating temperature, turn the engine OFF .
  8.  
  9. Once again, disconnect the engine wiring harness from the ECT sensor.
  10.  
  11. Measure and note the ECT sensor resistance with the engine hot.
  12.  
  13. Compare the cold and hot ECT sensor resistance measurements with the accompanying chart.
  14.  



Click image to see an enlarged view

Fig. Fig. 2: Submerge the sensor in water and check the testing with the Engine Coolant Temperature (ECT) sensor chart

  1. If readings do not approximate those in the chart, the sensor may be faulty.
  2.  

REMOVAL & INSTALLATION



See Figures 3, 4, 5 and 6

  1. Drain the engine coolant.
  2.  
  3. Disconnect the ECT sensor wiring.
  4.  



Click image to see an enlarged view

Fig. Fig. 3: View of the common Engine Coolant Temperature (ECT) sensor

  1. Remove the sensor and gasket.
  2.  



Click image to see an enlarged view

Fig. Fig. 4: Place a wrench over the ECT sensor and turn to loosen



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Fig. Fig. 5: Hold the ECT sensor ...



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Fig. Fig. 6: ... and place permatex on the sensor before installing

To install:
  1. Install the new sensor with gasket. Tighten the sensor to 17 ft. lbs. (25 Nm).
  2.  
  3. Connect the wiring to the sensor.
  4.  
  5. Refill the engine with coolant and water mixture.
  6.  

 
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