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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Vibe. 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, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Select ECT sensor parameter on scan tool. Is ECT sensor value more than or equal to 284°F (140°C)? If yes, go to step  5. If no, go to next step.
  3. Select ECT sensor parameter on scan tool. Is ECT sensor value less than or equal to -40°F (-40°C)? If yes, go to step  7. If no, go to next step.
  4. Use scan tool to clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start engine. Operate vehicle within CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to step  2. If no, go to DIAGNOSTIC AIDS .
  5. Turn ignition switch to RUN position, engine OFF. Disconnect ECT sensor 2-pin harness connector. Select ECT sensor parameter on the scan tool. Is ECT sensor value equal to -40°F (-40°C)? If yes, go to step  13. If no, go to next step.
  6. Turn ignition OFF. Disconnect PCM White 34-pin harness connector. Check ECT sensor input circuit for a short to ground. Ensure input circuit is not shorted to the sensor ground circuit. Repair as necessary. Was a repair necessary? If yes, go to step  15. If no, go to step  14.
  7. Disconnect ECT sensor 2-pin harness connector. Jump ECT input circuit and sensor ground circuit together at ECT sensor harness connector. Select ECT sensor parameter on scan tool. Is ECT sensor value more than or equal to 284°F (140°C)? If yes, go to step  10. If no, go to step  11.
  8. Jump the ECT input circuit at ECT sensor harness connector to chassis ground. Select ECT sensor parameter on scan tool. Is ECT sensor value more than or equal to 284°F (140°C)? If yes, go to step  10. If no, go to step  11.
  9. Check for faulty electrical connections at ECT sensor. Repair as necessary. Was a repair necessary? If yes, go to step  15. If no, go to step  13.
  10. Turn ignition OFF. Disconnect PCM White 34-pin harness connector. Check ECT sensor ground circuit for an open. Repair as necessary. Was a repair necessary? If yes, go to step  15. If no, go to step  12.
  11. Turn ignition OFF. Disconnect PCM 34-pin harness connector. Check ECT sensor input circuit for an open. Repair as necessary. Was a repair necessary? If yes, go to step  15. If no, go to step  12.
  12. Check for a faulty ECT circuit terminal connection at PCM. Repair as necessary. Was a repair necessary? If yes, go to step  15. If no, go to step  14.
  13. Replace ECT sensor. After repair, go to step  15.
  14. Replace PCM. After repair, go to step  15.
  15. Using scan tool, clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start engine. Operate vehicle within CONDITIONS FOR RUNNING DTC . Does DTC run and pass? If yes, go to next step. If no, go to step  2.
  16. Using scan tool, observe stored information, CAPTURE INFO. Does scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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