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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 218 (Engine Controls - Basic Diagnostic Procedures - 4.8L, 5.3L & 6.0L - Flex Fuel & Gasoline Engines) >> Ignition Systems >> Electronic Ignition System Diagnosis >> Diagnostic Procedures

Diagnostic Procedures

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  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article. After performing diagnostic system check, go to next step.
  2. Crank engine. Observe engine speed parameter with a scan tool. Does scan tool display engine RPM? If yes, go to next step. If no, go to step  15 .
  3. Is DTC P0335, P0336, or P0351-P0358 also set? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article. If DTC P0335, P0336, or P0351-P0358 are not set, go to next step.
  4. Idle engine. Observe misfire current counters on scan tool. Does scan tool display any misfire current counters incrementing? If yes, go to next step. If no, go to DIAGNOSTIC AIDS  .
  5. Do misfire current counters increment for most cylinders on one bank of engine? If yes, go to step  11 . If no, go to next step.
  6. Inspect spark plug wire for open circuits, cracks, or improper seating of terminals at spark plug or coil before proceeding with test. Inspect for spark at spark plug using Spark Tester (J-26792) while cranking. A few sparks, then nothing is considered no spark. Is adequate spark present? If yes, go to step  32 . If no, go to next step.
  7. Measure spark plug wire resistance. Is resistance more than 1000 ohms per foot? If yes, go to step  31 . If no, go to next step.
  8. Turn ignition off. Disconnect ignition coil that corresponds to Misfire Current counter that was incrementing. Turn ignition on, with engine off. Probe ignition 1 voltage circuit of ignition coil with a test light connected to a good ground. See Figure or Figure . Does test light illuminate? If yes, go to next step. If no, go to step  12 .
  9. Probe ignition 1 voltage circuit at ignition coil with a test light connected to ground circuit of ignition coil. Does test light illuminate? If yes, go to next step. If no, go to step  13 .
  10. Probe ignition 1 voltage circuit at ignition coil with a test light connected to low reference circuit of ignition coil. Does test light illuminate? If yes, go to step  19 . If no, go to step  14 .
  11. Inspect for an open INJ "A" or INJ "B" fuse. Is fuse open? If yes, go to step  28 . If no, go to step  22 .
  12. Disconnect main ignition coil 8-way connector. Probe ignition 1 voltage circuit at ignition coil main 8-way connector using test light connected to battery ground. Does test light illuminate? If yes, go to step  23 . If no, go to step  22 .
  13. Disconnect main ignition coil 8-way connector. Probe ignition 1 voltage circuit on harness side with a test light connected to ground circuit of ignition coil. Does test light illuminate? If yes, go to step  17 . If no, go to step  25 .
  14. Disconnect main ignition coil 8-way connector. Probe ignition 1 voltage circuit on harness side with a test light connected to low reference circuit of ignition coil. Does test light illuminate? If yes, go to step  18 . If no, go to step  27 .
  15. Turn ignition on, with engine off. Disconnect CKP sensor. See Figure . Measure voltage from CKP sensor 12-volt reference circuit and a good ground with DVOM. Compare measured voltage with system voltage. Is difference in voltage more than 0.5 volt? If yes, go to next step. If no, go to step  29 .
  16. Test for a short to ground in CKP 12-volt reference circuit or CMP sensor 12-volt reference circuit. See Figure or Figure . Did you find and correct condition? If yes, go to step  34 . If no, go to step  21 .
  17. Test for an intermittent and for a poor connection at ignition coil 8-way connector. Did you find and correct condition? If yes, go to step  34 . If no, go to step  24 .
  18. Test for an intermittent and for a poor connection at ignition coil 8-way connector. Did you find and correct condition? If yes, go to step  34 . If no, go to step  26 .
  19. Test for an intermittent and for a poor connection at ignition coil. Did you find and correct condition? If yes, go to step  34 . If no, go to step  30 .
  20. Test for an intermittent and for a poor connection at CKP sensor. Did you find and correct condition? If yes, go to step  34 . If no, go to step  29 .
  21. Test for an intermittent and for a poor connection at PCM. Did you find and correct condition? If yes, go to step  34 . If no, go to step  33 .
  22. Repair open or high resistance in ignition 1 voltage circuit between fuse block and splice. After repairs, go to step  34 .
  23. Repair open or high resistance in ignition 1 voltage circuit between splice and ignition coil connector. After repairs, go to step  34 .
  24. Repair open in ground circuit between main 8-way connector and ignition coil. After repairs, go to step  34 .
  25. Repair open in ground circuit. After repairs, go to step  34 .
  26. Repair open in low reference circuit between main 8-way connector and ignition coil. After repairs, go to step  34 .
  27. Repair open in low reference circuit between PCM and splice. After repairs, go to step  34 .
  28. Repair ignition 1 voltage for a short to ground. Replace fuse. After repairs, go to step  34 .
  29. Replace CKP sensor. After replacing sensor, go to step  34 .
  30. Replace ignition coil. After replacing ignition coil, go to step  34 .
  31. Replace spark plug wire. After replacing spark plug wire, go to step  34 .
  32. Replace spark plug. After replacing spark plug, go to step  34 .
  33. Replace PCM. See appropriate REMOVAL & INSTALLATION article. After replacing PCM, go to next step.
  34. Attempt to start engine. Does engine start and continue to run? If yes, go to next step. If no, go to step  2 .
  35. Clear DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Let engine reach operating temperature. Are there any DTCs that have not been diagnosed? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L "C", "K" & "N" SERIES - FLEX FUEL & GASOLINE article or DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 4.8L, 5.3L & 6.0L EXPRESS & SAVANA - GASOLINE article. If no DTC(s) are set, system is okay.
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