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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 335 (Engine Controls - Self-Diagnostics - 3.0L) >> Diagnostic Tests >> DTC P0125: ECT Excessive Time For Closed Loop Fuel Control >> 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. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS .
    2. NOTE: The cooling fans are commanded ON when certain Engine Coolant Temperature (ECT) DTCs are set.
  2. Is the cooling system coolant low? If yes, diagnose cooling system problem. 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 the ECT sensor. Inspect 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 the voltage from the signal circuit of the ECT sensor to a good ground with a DVOM. Is the voltage within 4.8-5.2 volts? If yes, go to next step. If no, go to step  8.
  6. Measure the 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 the 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 the 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 the resistance measurement of the ECT sensor within the specified range? If yes, go to next step. If no, go to step  12.
  10. Install the ECT sensor. After installing sensor, test for intermittent conditions. Refer to 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. Replace ECM. Perform ECM relearn procedures. See ENGINE CONTROL MODULE  under PROGRAMMING. After replacing ECM, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 90 seconds. Start engine. Operate vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC . You may also operate the vehicle within the conditions that you 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. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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