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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 258 (Engine Controls Self-Diagnostics - 2.2L) >> Diagnostic Tests >> DTC P0125: ECT Excessive Time To Enter Closed-Loop Fuel Control >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2003 GMC Sonoma and 2003 Chevrolet S10 Pickup. 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, go to next step.
    2. NOTE: The cooling fans are commanded ON when certain engine coolant temperature DTCs are set.
  2. Is the cooling system low on coolant? If yes, check cause of loss of 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. Inspect for corrosion on ECT sensor terminals, improper or corroded terminals at ECT harness connector, or loose terminals in 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 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 DVOM. Is 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 yes, 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 ECT sensor. Place sensor on a work surface away from any heat source. Allow 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 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. After installing sensor, refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L SONOMA & S10 PICKUP article.
  11. Test for an intermittent and for a poor connection at the PCM. 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 PCM. See appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Does the DTC run and pass? If yes, go to next step. If no, go to step  2 .
  15. Observe the stored information in 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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