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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 116 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0650: Malfunction Indicator Light Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. 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, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Is DTC P1634 also set? If yes, see DTC P1634: IMPROPER IGNITION 1 INPUT . If no, go to next step.
  3. Turn the ignition ON, with the engine OFF. Observe the Malfunction Indicator Lamp (MIL) display on the Instrument Panel Cluster (IPC). Is the MIL ON? If yes, go to next step. If no, go to step  6.
  4. Command the MIL OFF with a scan tool. Is the MIL OFF? If yes, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM. If no, go to next step.
  5. Test the MIL control circuit for a short to ground. If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  6. Turn the ignition OFF. Disconnect the PCM connector. Connect the test lamp between the MIL control circuit and ground. Turn the ignition ON, with the engine OFF. Is the test lamp ON? If yes, go to next step. If no, go to step  8.
  7. Test the MIL control circuit for a short to voltage. If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  11.
  8. Turn the ignition OFF. Connect the PCM connector. Disconnect the IPC connector. Connect the test lamp between the battery voltage and the MIL control circuit. Use the scan tool in order to command the MIL ON and OFF. Does the test lamp turn ON and OFF? If yes, go to next step. If no, go to step  10.
  9. Inspect for poor connections at the IPC harness connector. If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  10. Test for an open MIL control circuit. If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  11. Inspect for poor connections at the PCM. If a condition is found, repair as necessary. Did you find and correct the condition? If yes, go to step  14. If no, go to next step.
  12. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to step  14.
  13. Replace the IP cluster. See REMOVAL & INSTALLATION in appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs, go to next step.
  14. Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. With 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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