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Diagnostic Procedures

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  1. Did you perform the Diagnostic System Check-Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Clear the DTCs with a scan tool. Idle the engine at the normal operating temperature. Monitor the misfire current counters with a scan tool. Are any of the counters incrementing? If yes, go to step  4. If no, go to next step.
  3. Observe the Freeze Frame/Failure Records data for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observed. Does the DTC fail this ignition? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
  4. Turn OFF the ignition. Disconnect the fuel injector harness connector. Turn ON the ignition, with the engine OFF. Probe the ignition 1 voltage supply circuit of the appropriate fuel injector with a test lamp that is connected to a good ground. Does the test lamp illuminate? If yes, go to next step. If no, go to step  11.
  5. Connect the J 34730-375 Injector Test Lamp between the control circuit and the ignition 1 voltage supply circuit of the appropriate fuel injector. Crank the engine. Does the test lamp flash? If yes, go to step  9. If no, go to next step.
  6. Does the test lamp remain illuminated at all times? If yes, go to step  8. If no, go to next step.
  7. Test the control circuit of the fuel injector for an open and for a short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test the control circuit of the fuel injector for a short to ground. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  9. Inspect for poor connections at the harness connector of the fuel injector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Inspect for poor connections at the harness connector of the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
    11. NOTE: The INJ fuses also supplies voltage to the ignition coil modules. If the fuses are open inspect all related circuits for a short to ground.
  11. Repair the ignition 1 voltage supply circuit of the fuel injector for an open or for a short to ground. After repairs, go to step  14.
  12. Replace the fuel injector. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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