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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. Disconnect the PCM. Connect a test lamp between the Off/Run/Crank voltage circuit and a good ground. Turn the ignition switch to the ON and START positions. Does the test lamp illuminate with the ignition switch in both the ON and START positions? If yes, go to step  6. If no, go to next step.
  3. Did the test lamp illuminate for either ignition switch position? If yes, go to step  7. If no, go to next step.
  4. Test the Off/Run/Crank voltage circuit for an open and for a high resistance. Did you find and correct the condition? If yes, go to step  9. If no, go to next step.
  5. Test for an intermittent and for a poor connection at the ignition switch. Did you find and correct the condition? If yes, go to step  9. If no, go to step  7.
  6. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  9. If no, go to step  8.
  7. Replace the ignition switch. After repairs, go to step  9.
  8. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  9. 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.
  10. 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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