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Home >> Chevrolet >> 2000 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 1.8L >> Self-Diagnostic System >> Mil Inoperative >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Attempt to start and idle engine. If engine starts, go to next step. If engine does not start, go to step  6 .
  3. Observe instrument cluster operation. If all other instrument cluster functions operate properly, go to next step. If all other instrument cluster functions do not operate properly, diagnose instrument cluster as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
  4. Turn ignition off. Disconnect PCM 22-pin connector C3. Turn ignition on, with engine off. Using a fused jumper wire connected to ground, probe PCM harness connector C3 terminal No. 5 (MIL control circuit). See WIRING DIAGRAMS article. If MIL illuminates, go to step  21 . If MIL does not illuminate, go to next step.
  5. Turn ignition on, with engine off. Using a fused jumper wire connected to ground, backprobe instrument cluster connector C1 terminal No. 3 (MIL control circuit). See WIRING DIAGRAMS article. If MIL illuminates, go to step  14 . If MIL does not illuminate, diagnose instrument cluster as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT.
  6. Check for an open EFI fuse (15-amp) and IGN fuse (7.5-amp), faulty EFI main relay, and no ignition positive voltage. Repair as necessary. After repairs, go to step  22 . If fuse, relay and ignition voltage are okay, go to next step.
  7. Remove EFI main relay located in engine compartment fuse/relay box. Using test light connected to ground, probe EFI main relay connector terminal No. 9 (EFI fuse circuit). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  15 .
  8. Using test light connected to ground, probe EFI main relay connector terminal No. 11 (IGN fuse circuit). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  16 .
  9. Connect test light between EFI main relay connector terminals No. 11 (IGN fuse circuit) and No. 12 (ground circuit). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  17 .
  10. Connect test light between EFI main relay connector terminals No. 9 (EFI fuse circuit) and No. 10 (PCM circuit). See WIRING DIAGRAMS article. Attempt to start and idle engine. If engine starts, go to step  18 . If engine does not start, go to next step.
  11. Turn ignition off. Remove fused jumper wire. Install EFI main relay. Disconnect all PCM harness connectors. Turn ignition on. Using test light connected to ground, probe PCM harness connector C3 terminal No. 12 (ignition positive voltage circuit). See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step  19 .
  12. Using test light connected to battery voltage, probe the following PCM harness connector terminals:
    • 26-pin connector C1 terminal No. 13 (ground circuit).
    • 26-pin connector C1 terminal No. 14 (ground circuit).
    • 26-pin connector C1 terminal No. 26 (ground circuit).
    • 16-pin connector C2 terminal No. 16 (ground circuit).

    If test light illuminates on all terminals, go to next step. If test light does not illuminate on all terminals, go to step  20 .

  13. Check for short to ground in fuel tank pressure sensor, MAP sensor and TP sensor reference voltage circuits. Check if sensors are internally shorted. Repair as necessary. After repairs, go to step  22 . If circuits and sensors are okay, go to step  21 .
  14. Repair open in MIL control circuit. After repairs, go to step  22 .
  15. Repair open circuit between EFI fuse and EFI main relay. After repairs, go to step  22 .
  16. Repair open circuit between IGN fuse and EFI main relay. After repairs, go to step  22 .
  17. Repair open circuit between EFI main relay and ground connection. After repairs, go to step  22 .
  18. Replace EFI main relay. After repairs, go to step  22 .
  19. Repair open circuit between PCM and EFI main relay. After repairs, go to step  22 .
  20. Repair open circuit between PCM and ground connections. After repairs, go to step  22 .
  21. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  22. Turn ignition on. If MIL illuminates, go to next step. If MIL does not illuminate, go to step  2 .
  23. After repairs, using scan tool, clear DTC information. Road test vehicle within freeze frame conditions that set DTC. Start engine and let idle. Observe MIL. If MIL illuminates, perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. If MIL does not illuminate, system is okay.
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