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Fuel Injector Circuit Diagnosis (Except 2.2L & 3.4L)

NOTE: Fuel injector circuit diagnosis test information for 2.2L and 3.4L engines is not available from manufacturer.
  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing powertrain diagnostic system check, go to next step.
  2. Disconnect fuel injector harness connectors at intake manifold. Using a test light connected to ground, probe appropriate injector ignition feed circuits at fuel injector harness connector. Turn ignition on with engine off. If test light illuminates on both circuits, go to step  6. If test light does not illuminate on both circuits, go to next step.
  3. If test light illuminates on only one injector ignition feed circuit, go to step  5. If test light does not illuminate on only one injector ignition feed circuit, go to next step.
  4. Check injector fuse. If fuse is blown, go to step  10. If fuse is okay, go to step  11.
  5. Check for an open in appropriate injector feed circuit between PCM and injector harness connector. If open exists, go to step  12.
  6. Connect Fuel Injector Test Light (J-34730-380) to fuel injector harness connectors (PCM side) one at a time. Crank engine while observing test light. If test light does not flash at each injector, go to next step. If test light flashes at each injector, perform injector coil test. See INJECTOR COIL TEST (EXCEPT 2.2L & 3.4L) .
  7. If fuel injector test light illuminates constantly while engine is being cranked, go to next step. If fuel injector test light does not illuminate constantly while engine is being cranked, go to step  9.
  8. Install fuel injector test light on affected circuit. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on with engine off. If test light illuminates, go to step  13. If test light does not illuminate, go to step  16.
  9. Check for an open in injector control circuit between PCM and injector harness connectors. If open exists, go to step  12. If an open does not exist, go to step  14.
  10. Check for a short to ground in injector ignition feed circuit between PCM and injector harness connectors. If a short to ground exists, go to step  12.
  11. Repair open or short to ground on both injector ignition feed circuits. After repairs, go to step  17.
  12. Repair circuit as necessary. After repairs, go to step  17.
  13. Repair short to ground in injector control circuit between PCM and injector harness connectors. After repairs, go to step  17.
  14. Check PCM harness connectors for poor connections. If poor connection exists, go to next step. If poor connection does not exist, go to step  16.
  15. Repair terminal contact as necessary. After repairs, go to step  17.
  16. Replace PCM and reprogram PCM. Perform VTD password relearn procedure and crankshaft variation learn procedure. See COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION. After repairs, go to step  17.
  17. Using scan tool, clear DTCs. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start and continue to run, go to step  2.
  18. Let engine idle until normal operating temperature is reached. Retrieve DTCs. If no DTCs are set, system is okay. If any DTCs are set, perform appropriate DTC test. See appropriate SELF-DIAGNOSTICS article.
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