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Home >> Cadillac >> 2003 >> Seville STS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> System Tests >> Malfunction Indicator Lamp Always On >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition off. Disconnect the PCM. Turn ignition on, with the engine off. Observe the MIL. Is the MIL illuminated? If yes, go to next step. If no, go to step  5.
  3. Remove the Instrument Panel Cluster (IPC). See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Test the MIL control circuit for a short to ground between the PCM and the IPC. Did you find and correct the condition? If yes, go to step  6. If no, go to next step.
  4. Replace the IPC. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Did you complete the replacement? If yes, go to step  6.
  5. Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to next step.
  6. Operate the system in order to verify the repair. Did you correct the condition? If yes, system okay. If no, go to step  2.
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