LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Cadillac >> 1997 >> Catera >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Engine Testing 3.0L >> On-Board Diagnostic (OBD) System Check >> Mil Diagnosis
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Mil Diagnosis

  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Turn ignition on with engine off. If Malfunction Indicator Light (MIL) illuminates, go to step 7). If MIL does not illuminate, go to next step.
  3. Disconnect IAC motor connector. Using a test light connected to ground, probe IAC motor connector switched battery voltage circuit. If test light illuminates, go to next step. If test light does not illuminate, diagnose main relay circuit.
  4. Check instrument cluster ignition feed circuit fuse. If fuse is blown, go to step 10). If fuse is okay, go to next step.
  5. Turn ignition off. Disconnect ECM connector. Turn ignition on. Using a fused jumper wire, jumper MIL control circuit at ECM connector to ground. See the WIRING DIAGRAMS article. If MIL illuminates, go to step 11). If MIL does not illuminate, go to next step.
  6. Check for faulty bulb, open in ignition feed to bulb, or open or short to voltage in control circuit. Repair as necessary. After repairs, go to step 13).
  7. Using scan tool, check if any DTCs are present. If DTCs are present, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . If DTCs are not present, go to next step.
  8. Turn ignition off. Disconnect ECM connector. Turn ignition on with engine off. If MIL illuminates, go to next step. If MIL does not illuminate, go to step 12).
  9. Repair short to ground in MIL control circuit. Repair as necessary. After repairs, go to step 13).
  10. Repair short to ground in instrument cluster ignition feed circuit. Repair as necessary. After repairs, go to step 13).
  11. Check for poor ECM connections. Repair as necessary. After repairs, go to step 13). If connections are okay, go to next step.
  12. Replace ECM. Perform ECM relearn procedures. After repairs, go to next step.
  13. Start engine and observe MIL. MIL should momentarily illuminate, then go out. If MIL illuminates as specified, system is okay. If MIL does not illuminate as specified, perform ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  .
scientia non olet · About LEMON Manuals