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Diagnostic Procedure: Notes

NOTE: For terminal and circuit identification, see WIRING DIAGRAMS .
  1. If diagnostic system check has already been performed, go to next step. If diagnostic system check has not been performed, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
  2. Attempt to start engine. Does engine start and run? If yes, go to step  14. If no, go to next step.
  3. Turn ignition OFF. Remove underhood fuse block cover. Probe COIL/MDL fuse in underhood fuse block with a test light that is connected to a good ground. Does test light illuminate on any test points of the fuse? If yes, go to step  35. If no, go to next step.
  4. Turn ignition ON with the engine OFF. Probe COIL/MDL fuse in underhood fuse block with a test light that is connected to a good ground. Does the test light illuminate on both test points of the fuse? If yes, go to step  11. If no, go to next step.
  5. Does test light illuminate on one test point of COIL/MDL fuse? If yes, go to next step. If no, see ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in appropriate GENERATORS & REGULATORS article in ELECTRICAL.
  6. Turn ignition OFF. Disconnect Ignition Control (IC) module bank 1 (front) electrical connector. Test ignition 1 voltage circuit between COIL/MDL fuse and IC module bank 1 for a short to ground. See Figure or Figure . Repair as necessary. After repairs, go to step  43. If no short found, go to next step.
  7. Turn ignition OFF. Disconnect IC module bank 2 (rear) electrical connector. Test ignition 1 voltage circuit between COIL/MDL fuse and IC module bank 2 for a short to ground. See Figure. Repair as necessary. After repairs, go to step  43. If no short found, go to next step.
  8. Turn ignition OFF. Replace open COIL/MDL fuse. Connect IC module bank 1 electrical connector. Turn ignition ON, with the engine OFF. Does the DIS fuse open? If yes, go to next step. If no, go to step  10.
  9. Turn ignition OFF. Replace the open COIL/MDL fuse. Disconnect IC module bank 1 (front) electrical connector. Remove IC module from ignition coil assembly bank 1. Connect a 10-amp fused jumper wire between ignition 1 voltage circuit of IC module electrical connector and ignition 1 voltage terminal of IC module bank 1. Connect a jumper wire between the ground circuit of IC module electrical connector and ground terminal of IC module bank 1. Turn ignition ON, with the engine OFF. Does fuse in jumper wire open? If yes, go to step  23. If no, go to step  25.
  10. Turn ignition OFF. Disconnect IC module bank 2 (rear) electrical connector. Remove IC module from ignition coil assembly bank 2. Connect a 10-amp fused jumper wire between ignition 1 voltage circuit of IC module electrical connector and ignition 1 voltage terminal of IC module bank 2. See Figure. Connect a jumper wire between the ground circuit of the IC module electrical connector and ground terminal of the IC module bank 2. Turn ignition ON, with the engine OFF. Does fuse in jumper wire open? If yes, go to step  24. If no, go to step  26.
  11. Turn ignition OFF. Disconnect IC module electrical connector bank 1 (front). Turn ignition ON, with the engine OFF. Probe ignition 1 voltage circuit of IC module electrical connector with a test light that is connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step  29.
  12. Turn ignition OFF. Disconnect IC module electrical connector bank 2 (rear). Turn ignition ON, with the engine OFF. Probe ignition 1 voltage circuit of IC module electrical connector with a test light that is connected to a good ground. Does test light illuminate? If yes, go to next step. If no, go to step  30.
  13. Turn ignition OFF. Probe ground circuit of IC module bank 1 electrical connector with a test light that is connected to battery voltage. Does the test light illuminate? If yes, go to step  32. If no, go to step  31.
  14. Observe the Misfire Current Counters with a scan tool. Do any of the cylinders indicate an increasing misfire count? If yes, go to next step. If no, see INTERMITTENT CONDITIONS under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article.
  15. Turn ignition OFF. Disconnect IC module for cylinders which indicated a misfire. Turn ignition ON, with the engine OFF. Probe ignition 1 voltage circuit of IC module with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  33.
  16. Turn ignition OFF. Probe ground circuit of IC module electrical connector for bank of cylinders identified as misfiring with a test light that is connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step  34.
  17. Turn ignition OFF. Disconnect ignition coil assembly from spark plugs on the bank of cylinders which indicated a misfire condition. Inspect the ignition coil housing assembly and the spark plug boots for visible cracks, deterioration, or other damage, any carbon tracking or other signs of arcing, any missing or damaged spark plug boot springs, or a missing, loose, or corroded grounding spring from coil housing to cam cover. Repair as necessary. After repairs, go to step  44. If no problem found, go to next step.
    18. WARNING: The ignition coils secondary voltage output capabilities are very high, more than 40,000 volts. Avoid body contact with high ignition voltage secondary components when the engine is running, to prevent personal injury.
  18. Connect electrical connector to IC module. Install Ignition System Diagnosis Harness (J-36012-A) spark plug jumper wires between the ignition coils and the spark plugs. Connect HEI Spark Tester (J-26792) to the spark plug jumper wire for the cylinder identified as misfiring. Attach the clamp end of HEI Spark Tester to a good engine ground. Attach a jumper wire from the grounding spring on the ignition coil housing to a good engine ground. Remove both fuel injector fuses. Observe HEI Spark Tester. Crank engine. Does the spark jump the tester gap? If yes, go to next step. If no, go to step  22.
  19. Remove the spark plug for the cylinder that was identified as misfiring. Does the spark plug indicate oil contamination? If yes, repair as necessary. See appropriate article in ENGINES. If no, go to next step.
  20. Does the spark plug indicate coolant contamination? If yes, repair as necessary. See appropriate article in ENGINES. If no, go to next step.
  21. Exchange suspected spark plug with a spark plug from a different cylinder. Install Ignition System Diagnosis Harness spark plug jumper wires between the ignition coils and spark plugs for affected cylinder bank. Install a jumper wire between coil housing ground spring and a good engine block ground. Install both fuel injector fuses. Monitor misfire current counters with a scan tool. Start engine. Does misfire move with spark plug? If yes, go to step  38. If no, repair as necessary. See appropriate article in ENGINES.
    22. NOTE: Use the correct test harness when connecting Ignition Module Tester (J-43298) to the IC module.
  22. Turn ignition OFF. Remove IC module from ignition housing assembly. If the intermediate mating connector came off with IC module, remove mating connector. Connect engine harness electrical connector to the IC module. Connect Ignition Module Tester to IC module. The Green power LED on Ignition Module Tester must be illuminated when ignition is ON. Turn ignition ON, with the engine OFF. Observe Ignition Module Tester. Momentarily press the test button on the Ignition Module Tester. All four Red LEDs should turn ON brightly. Crank engine. Does the four LEDs flash ON and OFF as engine is cranked? If yes, go to step  27. If no, go to step  28.
  23. Test for an intermittent and for a poor connection at the IC module bank 1 electrical connectors. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  39.
  24. Test for an intermittent and for a poor connection at the IC module bank 2 electrical connector. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  40.
  25. Test for an intermittent and for a poor connection at the intermediate mating connector between IC module and ignition coil assembly bank 1. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  41.
  26. Test for an intermittent and for a poor connection at the intermediate mating connector between IC module and ignition coil assembly bank 2. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  42.
  27. Test for an intermittent and for a poor connection at intermediate mating connector between affected IC module and ignition coil assembly. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  36.
  28. Test for an intermittent and for a poor connection at electrical connector of IC module for cylinders which indicated a misfire. Repair as necessary. After repairs, go to step  44. If connectors are okay, go to step  37.
  29. Repair high resistance or open in ignition 1 voltage circuit of IC module bank 1. After completing repair, go to step  44.
  30. Repair high resistance or open in ignition 1 voltage circuit of IC module bank 2. After completing repair, go to step  44.
  31. Repair high resistance or open in ground circuit of IC module bank 1. After completing repair, go to step  44.
  32. Repair high resistance or open in ground circuit of IC module bank 2. After completing repair, go to step  44.
  33. Repair high resistance or open in ignition 1 voltage circuit of affected IC module. After completing repair, go to step  44.
  34. Repair high resistance or open in ground circuit of affected IC module. After completing repair, go to step  44.
  35. Repair short to battery voltage in ignition 1 voltage circuit to IC modules. After completing repair, go to step  44.
  36. Replace affected ignition coil assembly. After completing repair, go to step  44.
  37. Replace affected IC module. After completing repair, go to step  44.
  38. Replace spark plug. Did you complete the replacement? After completing repair, go to step  44.
  39. Replace IC module bank 1. After completing repair, go to step  44.
  40. Replace IC module bank 2. After completing repair, go to step  44.
  41. Replace ignition coil assembly bank 1. After completing repair, go to step  44.
  42. Replace ignition coil assembly bank 2. After completing repair, go to step  44.
  43. Replace COIL/MDL fuse. After completing repair, go to next step .
  44. Were you sent to this diagnostic test from the Engine Cranks But Does Not Run diagnostic test? If yes, go to step  46. If no, go to next step.
  45. Were you sent to this diagnostic test from the DTC P0300 diagnostic test? If yes, go to step  47. If no, go to step  48.
  46. Attempt to start the engine. Does engine start and run? If yes, go to step  48. If no, see ENGINE CRANKS BUT DOES NOT RUN  under NO-START DIAGNOSIS.
  47. Clear DTCs with a scan tool. Turn ignition OFF for 30 seconds. Operate vehicle within the conditions for running DTC P0300. See DTC P0300: ENGINE MISFIRE DETECTED under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article. You may also operate vehicle within conditions that you observed from Freeze Frame/Failure Records. Did DTC fail during this ignition cycle? If yes, see DTC P0300: ENGINE MISFIRE DETECTED under DIAGNOSTIC TESTS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article. If no, go to next step.
  48. Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.6L DEVILLE & SEVILLE article. If no, system is okay.
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