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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 274 (Engine Controls - Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0125: ECT Excessive Time To Enter Closed Loop >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
    2. NOTE: The cooling fans are commanded on when certain ECT DTCs are set.
  2. Is the cooling system coolant low? If yes, add coolant. If no, go to next step.
  3. Test and verify the proper operation of the thermostat. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  4. Disconnect ECT sensor. Check for corrosion on the ECT sensor terminals, improper or corroded terminals at the ECT harness connector, or loose terminals in the ECT harness connector. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  5. Measure voltage from the signal circuit of the ECT sensor to a good ground with a DVOM. Is voltage within 4.8-5.2 volts? If yes, go to next step. If no, go to step  8.
  6. Measure voltage from the signal circuit of the ECT sensor to the low reference circuit of the ECT sensor with a DVOM. Is the voltage within 4.8-5.2 volts? If yes, go to step  9. If no, go to next step.
  7. Test ECT sensor low reference circuit for high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Test ECT sensor signal circuit for high resistance. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  9. Turn ignition off. Remove the ECT sensor. Place the sensor on a work surface away from any heat source. Allow the sensor to reach the ambient air temperature for 30-60 minutes. Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer. Measure the resistance of the ECT sensor and record the value. Compare the resistance measurement of the ECT sensor to the ambient air temperature on 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 next step. If no, go to step  12.
  10. Install ECT sensor. Problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L & 3.0L VUE article.
  11. Test for an intermittent and for a poor connection at the ECM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  12. Replace ECT sensor. After replacing sensor, go to step  14.
  13. Turn ignition off. Replace ECM. Perform ECM relearn procedure. See ELECTRONIC CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  14. Using scan tool, clear DTCs. Turn ignition off for 30 seconds. Operate vehicle within the conditions for running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate vehicle within the conditions observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. With a scan tool, observe the stored information, Capture Info. 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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