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Home >> Pontiac >> 2003 >> Aztek FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0116: ECT Sensor Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
    2. NOTE: The cooling fans are commanded ON when certain Engine Coolant Temperature (ECT) DTCs are set.
  2. Is cooling system low on coolant? If yes, repair and refill cooling system. If no, go to next step.
  3. Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer. After checking temperature, go to next step.
    4. NOTE: Vehicle needs to have been OFF for at least 8 hours for the ECT and IAT to be at ambient temperature. The vehicle should not have changed environments during this time.
  4. Has the engine been OFF for at least 8 hours? If yes, go to step  7. If no, go to next step.
  5. Remove the IAT sensor. Remove the ECT sensor. Place sensors on a work surface away from any heat source. Allow the sensors to reach the ambient air temperature for 30-60 minutes, then go to next step.
  6. Connect the IAT sensor to the electrical connector, but DO NOT install it. Insulate sensor from any engine heat source. Connect the ECT sensor to the electrical connector, but DO NOT install it. Insulate sensor from any engine heat source, then go to next step.
  7. Turn ON the ignition. Using scan tool, take a snapshot of the Engine Data List. Review the snapshot data that was taken with the scan tool. Observe the ECT Sensor parameter with a scan tool. Observe the IAT Sensor parameter with a scan tool. Is the difference between the ECT sensor parameter and IAT sensor parameter more than 27°F? If yes, go to next step. If no, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
  8. Observe the recorded IAT Sensor parameter. Is the difference between the IAT Sensor parameter and the ambient air temperature less than 14°F? If yes, go to next step. If no, go to step  10.
  9. Observe the recorded ECT Sensor parameter. Is the difference between the ECT Sensor parameter and the ambient air temperature less than 14°F? If yes, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, go to step  12.
  10. Disconnect the IAT sensor. Test for an intermittent and for a poor connection at the IAT sensor. Did you find and correct the condition? If yes, go to step  25. If no, go to next step.
    11. NOTE: DO NOT hold the IAT sensor by the probe.
  11. Using a DVOM, measure sensor resistance between the IAT signal and IAT low reference terminals record the value. Observe the recorded ambient air temperature. Compare the resistance measurement of the IAT sensor to the ambient air temperature using the Temperature vs. Resistance table. Refer to SENSOR OPERATING RANGE CHARTS - TRUCKS article. Is resistance within the specified range? If yes, go to step  14. If no, go to step  22.
  12. Disconnect the ECT sensor. Inspect ECT sensor for leaking engine coolant internally through the sensor, corrosion on ECT sensor terminals, or corrosion on ECT harness connector terminals. Did you find and correct the condition? If yes, go to step  25. If no, go to next step.
    13. NOTE: DO NOT hold the ECT sensor by the probe.
  13. Using DVOM, measure sensor resistance between the ECT signal and ECT low reference terminals and record the value. Observe the recorded ambient air temperature. Compare the resistance measurement of the ECT sensor to the ambient air temperature using the Temperature vs. Resistance table. Refer to SENSOR OPERATING RANGE CHARTS - TRUCKS article. Is resistance measurement of the ECT sensor within the specified range? If yes, go to step  15. If no, go to step  23.
  14. Measure the voltage from the IAT signal circuit to a good ground with a DVOM. Is voltage within 4.8-5.2 volts? If yes, go to step  16. If no, go to step  17.
  15. Measure the voltage from the ECT signal circuit to a good ground with a DVOM. Is voltage within 4.8-5.2 volts? If yes, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, go to step  19.
    16. NOTE: All electrical components and accessories must be turned OFF. Performing this step will disable the diagnostic for 8 hours.
  16. Turn ignition off for 90 seconds to allow the control modules to power down. Measure the resistance from the low reference circuit of the IAT sensor to a good ground. Is resistance less than 5 ohms? If yes, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article. If no, go to step  18.
  17. Test the IAT signal circuit for a high resistance. Did you find and correct the condition? If yes, go to step  25. If no, go to step  20.
  18. Test the IAT low reference circuit for a high resistance. Did you find and correct the condition? If yes, go to step  25. If no, go to step  20.
  19. Test the ECT signal circuit for a high resistance short to ground. Did you find and correct the condition? If yes, go to step  25. If no, go to step  21.
  20. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  25. If no, go to step  24.
  21. Test for shorted terminals and poor connections at the PCM. Did you find and correct the condition? If yes, go to step  25. If no, go to step  24.
  22. Replace IAT sensor. After replacing sensor, go to step  25.
  23. Replace ECT sensor. After replacing sensor, go to step  25.
  24. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  25. Reassemble components as necessary. After reassembly, go to next step.
    26. NOTE: This DTC will not run without the ignition being OFF for at least 8 hours.
  26. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  27. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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