Diagnostic Procedures
- 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.
- Clear the DTCs with a scan tool. Start the engine. Allow the engine to reach operating temperature. Monitor the misfire current counters with a scan tool. Are any of the misfire current counters incrementing? If yes, go to step 4. If no, go to next step.
- 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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Does the DTC fail this ignition cycle? If yes, go to next step. If no, see DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect the fuel injector which displays the highest number of misfire current counters. Turn ignition on, with engine off. Probe the ignition voltage circuit of the fuel injector with a test light connected to a good ground. Does the test light illuminate? If yes, got o next step. If no, go to step 11.
- Connect the Injector Test Light between the control circuit and the ignition voltage circuit of the fuel injector harness connector. Start the engine. Does the test light blink? If yes, go to step 9. If no, go to next step.
- Does the Injector Test Light remain illuminated at all times? If yes, go to step 8. If no, go to next step.
- Test the control circuit of the fuel injector for a short to voltage or an open. Did you find and correct the condition? If yes, go to step 14. If no, go to step 10.
- Test the fuel injector control circuit for a short to ground. Did you find and correct the condition? If yes, go to step 14. If no, go to step 13.
- Test for an intermittent and/or poor connections at the fuel injector. Did you find and correct the condition? If yes, go to step 14. If no, go to step 12.
- Test for an intermittent and/or poor connections at the PCM. Did you find and correct the condition? If yes, go to step 14. If no, go to step 13.
- Repair the fuel injector ignition voltage circuit for an open or a short to ground. Did you complete the repair? If yes, go to step 14.
- Replace the fuel injector. See FUEL RAIL & INJECTORS under FUEL SYSTEMS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to step 14.
- Replace PCM. See POWERTRAIN CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - DEVILLE & SEVILLE article. Did you complete the replacement? If yes, go to next step.
- Clear the DTCs with a scan tool. Turn off the ignition for 30 seconds. Start the engine and operate vehicle within the Conditions For Running DTC. You may also operate vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle? If yes, go to step 2. If no, go to next step.
- Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.