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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 1.8L VIBE article.
    2. NOTE: This procedure assumes that the Malfunction Indicator Light (MIL) and the Data Link Connector (DLC) function normally. Verify MIL operation and DLC communication are OK before performing this procedure.
  2. Turn ignition switch to OFF position. Disconnect all 4 fuel injector harness connectors. Install a fuel injector test light into each fuel injector harness connector. Observe the injector test light for each injector while cranking the engine. Does the injector test light flash for each injector circuit while cranking the engine? If yes, go to FUEL INJECTOR COIL TEST - ENGINE COOLANT TEMPERATURE BETWEEN 50-95°F (10-35°C)  . If no, go to next step.
  3. Did the fuel injector test light flash for at least one fuel injector circuit while cranking the engine? If yes, go to step  5 . If no, go to next step.
  4. Check for an open in the fuel injector power circuit between the ignition switch and splice S114 and/or an open in the PCM ground circuits. Repair as necessary. After repair, go to step  12 .
  5. Was the injector test light illuminated steady for any fuel injector circuit? If yes, go to next step. If no, go to step  8 .
  6. Turn ignition switch to OFF position. Install the fuel injector test lead in any fuel injector circuit that stays ON. Disconnect PCM 34-pin harness connector C1. Turn ignition switch to RUN position, engine OFF. Does the fuel injector test light illuminate? If yes, go to next step. If no, go to step  11 .
  7. Repair the short to ground in the faulty fuel injector control circuit between the PCM and the fuel injector. After repair, go to step  12 .
  8. Remove the injector test light from the fuel injector harness connector. Connect a test light from ground to the ignition positive voltage side of the fuel injector harness connector that did not flash. Turn ignition switch to RUN position, engine OFF. Does the test light illuminate? If yes, go to step  10 . If no, go to next step.
  9. Repair the open in the ignition feed circuit between the fuel injector and splice S114. After repair, go to step  12 .
  10. Check for an open in the faulty fuel injector control circuit. Repair as necessary. Repeat steps  5 - 10 until the injector test light flashes in all 4 fuel injector circuits. Was a repair necessary? If yes, go to step  12 . If no, go to next step.
  11. Replace the PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - VIBE article. After repair, go to next step.
  12. Use scan tool to clear DTCs. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate vehicle within the conditions that caused the concern. Does the fuel system now operate properly? If yes, go to next step. If no, go to DIAGNOSTIC AIDS  .
  13. With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 1.8L VIBE article. If no, system is okay at this time.
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