Envoy, Rainer, Trailblazer 2006-2007

Testing

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Fig. Engine Coolant Temperature (ECT) sensor connector: (A) ECT sensor signal, (B) low reference-4.2L engine



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Fig. Engine Coolant Temperature (ECT) sensor connector: (A) low reference, (B) ECT sensor signal -5.3L and 6.0L engines

  1. Disconnect the Engine Coolant Temperature (ECT) sensor.
  2.  
  3. Turn ON the ignition, with the engine OFF.
  4.  
  5. Measure for the proper range of 4.9-5.2 volts between the ECT sensor signal circuit and a good ground with a Digital Multi-Meter (DMM).
  6.  
  7. If the voltage is less than 4.9 volts, test the ECT sensor signal circuit for a high resistance short to ground.
  8.  
  9. If the ECT sensor signal circuit tests normal, and the voltage is still not within the proper range, then replace the PCM.
  10.  
  11. Remove and test the ECT sensor. Measure and record the resistance of the ECT sensor at various ambient temperatures: -39°C-+120°C (-38°F-+248°F) 52,700-100 ohms.
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  13. If the resistance measurements of the ECT sensor are out of range, replace the sensor.
  14.  
  15. If the ECT sensor tests normal and the DTC continues to set, then replace the PCM.
  16.  

 
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