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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 106 (Engine Controls Self-Diagnostics - 2.2L CNG) >> 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 2002 Chevrolet Cavalier. 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. Verify proper cooling system and thermostat operation. Was a cooling system repair made? If yes, go to step  11 . If no, go to next step.
  3. Using scan tool, establish communication with the AF ECM. Disconnect the ECT sensor. Additional DTCs may set. Clear DTCs when diagnosis is complete. Observe the ECT sensor data parameter. Does the ECT sensor data parameter indicate ECT voltage greater than 4.8 volts? If yes, go to next step. If no, go to step  7 .
  4. Connect a fused jumper between the ECT sensor connector signal and ground circuit terminals. Additional DTCs may set. Clear DTCs when diagnosis is complete. Does the ECT sensor data parameter indicate ECT voltage less than 0.019 volt? If yes, go to next step. If no, go to step  8 .
    5. WARNING: To avoid being burned, DO NOT remove radiator cap or surge tank cap while engine is hot. Cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed while engine and radiator are still hot.
  5. Install a thermometer in the engine cooling system in order to measure actual coolant temperature. Start and idle engine. Allow engine to operate until ECT sensor data parameter no longer increases (temperature has stabilized). Observe ECT sensor data parameter. Measure the actual engine coolant temperature. Compare the ECT sensor data parameter to actual engine coolant temperature. Does the ECT sensor data parameter indicate a temperature near the actual engine coolant temperature? If yes, go to next step. If no, go to step  9 .
  6. The fault is not present. See DIAGNOSTIC AIDS  . Are any DTCs stored that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, refer to INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  7. Inspect the ECT signal circuit for a shorted or low resistance to ground condition. Repair wiring or terminals as necessary. Was a wiring or terminal repair made? If yes, go to step  11 . If no, go to step  10 .
  8. Inspect the ECT signal and ground circuits for an open or high resistance condition. Inspect the PCM connector, the AF ECM connector and the ECT sensor connector for proper terminal contact. Repair wiring or terminals as necessary. Was a wiring or terminal repair made? If yes, go to step  11 . If no, go to step  10 .
  9. Replace ECT sensor. When complete, go to step  11 .
  10. Replace AF ECM. See ALTERNATE FUEL ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CARS article. Program (flash) AF ECM with correct vehicle software and calibration. See ALTERNATE FUEL ENGINE CONTROL MODULE  under PROGRAMMING. After performing repairs and procedures, go to next step.
  11. Using scan tool, clear the DTC information from BOTH control modules. Operate the vehicle under the Conditions for Running the DTC. See CONDITIONS FOR RUNNING DTC  . Using the scan tool parameter DTC STATUS, ensure that this DTC runs. Did this DTC RUN and PASS? If yes, system is okay. If no, go to step  2 .
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