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Home >> Buick >> 2002 >> Century Custom >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 3.1L Engine >> System Tests >> Mil On Steady >> 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. With a scan tool observe the DTCs. Are any DTCs set? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Turn ignition off. Observe the MIL on the Instrument Panel Cluster (IPC). Is MIL ON? If yes, go to step  6. If no, go to next step.
  4. Install a scan tool. Command the MIL ON and OFF several times while monitoring the IPC. Does the MIL turn ON and OFF when commanded? If yes, problem is intermittent. If no, go to next step.
  5. Test the MIL control circuit for a short to ground. After repairs, go to step  7.
  6. Test the MIL control circuit for a short to voltage. Repair as necessary. After repairs, go to next step.
  7. Install a scan tool. Command the MIL ON and OFF several times while monitoring the IPC. Does the MIL turn off when commanded? If yes, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS . If no, go to step  2.
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