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Home >> Saturn >> 2002 >> SC2 Automatic, MP6 >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Testing & Engine Component Testing >> Ignition Systems >> Ignition Relay Diagnosis (2.2L - Cavalier - CNG) >> Diagnostic Procedures

Diagnostic Procedures

  1. If alternative fuels engine controls diagnostic system check has been performed, go to next step. If alternative fuels engine controls diagnostic system check has not been performed, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing alternative fuels engine controls diagnostic system check, go to next step.
  2. Turn ignition off. Remove and inspect CNG fuse (20-amp) located in underhood fuse block. See Figure. Remove and inspect PCM fuse (10-amp) located in instrument panel fuse block. If either fuse is blown, go to step  13. If both fuses are okay, go to next step.
  3. Reinstall CNG and PCM fuses. Turn ignition on. Using a test light connected to ground, probe each terminal of CNG and PCM fuse. If test light illuminates at all terminals, go to step  5. If test light does not illuminate at all terminals, go to next step.
  4. Check for poor fuse contact. Check for proper voltage of supply circuit to malfunctioning fuse. See POWER DISTRIBUTION article in WIRING DIAGRAMS. Repair as necessary. After repairs, go to step  22.
  5. Turn ignition off. Locate and disconnect Alternate Fuel Engine Control Module (AF ECM) connectors. AF ECM is located behind left front fascia, below headlight. Turn ignition on. Using a test light connected to ground, probe AF ECM Blue connector C001 terminals No. 13 (Pink wire), No. 15 (Pink wire) and No. 16 (Orange wire). See Figure. If test light illuminates at all terminals, go to next step. If test light does not illuminate at all terminals, go to step  14.
  6. Using a test light connected to battery voltage, probe Black wire at AF ECM Clear/White connector C002 terminals No. 21, 22, 23 and 24. See Figure. If test light illuminates at all terminals, go to step  20. If test light does not illuminate at all terminals, go to step  14.
  7. Turn ignition off and wait 30 seconds. Monitor Fuel Indicator Light (FIL) located on fuel gauge select switch to left of steering column. Turn ignition on. If FIL illuminates for 2 second bulb check, go to step  9. If FIL does not illuminate for 2 second bulb check, go to next step.
  8. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 87 (Red wire). Ignition relay is located below left front headlight. See Figure. If test light illuminates, go to FUEL INDICATOR LIGHT INOPERATIVE (CNG) under SYSTEM TESTS in appropriate ANALOG INSTRUMENT PANELS article. If test light does not illuminate, go to step  10.
  9. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 87 (Red wire). Ignition relay is located below left front headlight. See Figure. Observe test light. Turn ignition off. If test light is illuminated with ignition off, go to step  15. If test light is not illuminated with ignition off, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article.
  10. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 30 (Orange wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  16.
  11. Ensure ignition is on. Using test light connected to ground, backprobe ignition relay terminal No. 85 (Pink wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  17.
  12. Disconnect ignition relay. Ignition relay is located below left headlight. See Figure. Ensure ignition is on. Connect test light between ignition relay connector terminals No. 85 (Pink wire) and No. 86 (Black wire). If test light is illuminated, go to step  19. If test light is not illuminated, go to step  18.
  13. Check for cause of blown fuse. For blown CNG fuse, check for the following conditions:
    • Shorted GMS/MCV circuit.
    • Shorted fuel gauge select switch circuit.
    • Shorted lock-off solenoid or circuit.
    • Shorted AF ECM or AF ECM battery voltage supply circuit.

    For blown PCM fuse, check for the following conditions:

    • Shorted ignition relay coil or circuit.
    • Shorted AF ECM or AF ECM ignition voltage supply circuit.
    • Shorted base vehicle circuit. See POWER DISTRIBUTION article in WRING DIAGRAMS.

    Repair as necessary. After repairs, go to step  22.

  14. Repair open in AF ECM circuit that did not illuminate test light. After repairs, go to step  22.
  15. Replace stuck ignition relay or repair short to battery voltage in Pink wire between CLS/PCM fuse (10-amp) located in instrument panel fuse block and ignition relay connector terminal No. 85. After repairs, go to step  22.
  16. Repair open in Orange wire between ignition relay connector terminal No. 30 and splice S001 located approximately 1.5" (3.5 cm) from the 4 relay break outs, towards AF ECM connector break outs. After repairs, go to step  22.
  17. Repair open in Pink wire between ignition relay connector terminal No. 85 and splice S028 located approximately 6" (14 cm) from ignition relay connector. After repairs, go to step  22.
  18. Repair open in Black wire between ignition relay connector terminal No. 86 and ground connection located on left side of engine/transmission. After repairs, go to step  22.
  19. Replace ignition relay. After repairs, go to step  22.
  20. Check for poor connections at AF ECM connectors. Repair as necessary. After repairs, go to step  22. If connections are okay, go to next step.
  21. Replace AF ECM. See ALTERNATE FUEL ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL, OVERHAUL & INSTALLATION - CAVALIER & SUNFIRE article. Program (flash) AF ECM with correct vehicle software and calibration. See ALTERNATE FUEL ENGINE CONTROL MODULE under PROGRAMMING in SELF-DIAGNOSTICS - 2.2L CAVALIER - CNG article. After performing repairs and procedures, go to next step.
  22. Turn ignition off. Remove all test equipment. Reconnect any disconnected components and/or connectors. Using scan tool, clear DTCs from AF ECM and PCM. Turn ignition off for 30 seconds. Start engine and allow to idle. Start engine and operate vehicle noting operation of Fuel Indicator Light (FIL) and Malfunction Indicator Light (MIL). Observe vehicle performance and driveability in gasoline and alternate fuel modes. If FIL or MIL do not illuminate and vehicle performs normally, system is okay at this time. If FIL or MIL illuminate or vehicle does not performs normally, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article.
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