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Home >> Saturn >> 2003 >> Ion 1 Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0650: Mil Control Circuit >> Diagnostic Procedures
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Diagnostic Procedures

  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 whether the instrument cluster is operational. If the Instrument Panel (IP) is completely inoperative, repair instrument panel. Command the MIL ON and OFF with a scan tool. Does the MIL turn ON and OFF when commanded with a scan tool? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start engine. Operate the 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. Does the DTC fail this ignition? If yes, go to next step. If no, refer to INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 2.2L ION article.
  4. Turn OFF the ignition. Disconnect the ECM. Turn ON the ignition. Is the MIL OFF? If yes, go to next step. If no, go to step  10.
  5. Remove the fuse that supplies voltage to the IPC. Measure the voltage from the MIL control circuit to a good ground. Is the voltage less than 1.0 volt? If no, go to next step. If no, go to step  11.
  6. Turn OFF the ignition. Install the fuse that supplies voltage to the IPC. Turn ignition on, with engine off. Connect a 3-amp fused jumper wire between the MIL control circuit of the ECM and a good ground. Is the MIL illuminated? If yes, go to step  9. If no, go to next step.
  7. Test the MIL control circuit for an open or high resistance. Did you find and correct a condition? If yes, go to step  14. If no, go to next step.
  8. Test for an intermittent and for a poor connection at the IPC. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  9. 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.
  10. Test for a short to ground in the MIL control circuit. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  11. Repair short to voltage in the MIL control circuit. After repairs, go to step  14.
  12. Replace IPC. After replacement, go to step  14.
  13. Replace ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - ION article. Perform ECM relearn procedure. See ENGINE CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing ECM, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start engine. Operate the 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. Using a scan tool, observe the stored information, Capture Info. 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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