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Home >> GMC >> 2003 >> Jimmy 2D Utility, Part Time, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics - 4.3L >> Diagnostic Tests >> DTC P0125: Excessive Time To Enter Closed Loop Fuel Control >> Diagnostic Procedures

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. Is the cooling system coolant low? If yes, repair cause of coolant loss and refill system. 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. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, SONOMA & S10 PICKUP article. 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. Reinstall ECT sensor. Problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 4.3L ASTRO, BLAZER, JIMMY CANADIAN, SAFARI, 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. See appropriate REMOVAL & INSTALLATION article. After repairs, go to next step.
  13. Replace PCM. See appropriate REMOVAL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, 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 DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  6.
  15. 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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