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Home >> Cadillac >> 2002 >> Escalade EXT >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Ignition System >> Electronic Ignition System Diagnosis (4.3L, 5.0L & 5.7L) >> Diagnostic Procedure
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Diagnostic Procedure

  1. Perform Diagnostic System Check - Engine Controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS under SELF-DIAGNOSTIC SYSTEM in appropriate SELF-DIAGNOSTICS article. After performing Diagnostic System Check - Engine Controls, go to next step.
  2. Crank engine. Observe Engine Speed parameter with scan tool. Does scan tool display engine RPM? If yes, go to next step. If no, go to step  19.
  3. Check spark plug wires for open circuits, cracks, or improper seating of terminals at spark plugs, distributor, and ignition coil before proceeding with test. Check spark at plug with Spark Tester (J 26792) or equivalent while cranking. If there is no spark on one wire, check a second wire. A few sparks then nothing is considered no spark. Does spark occur on all cylinders? If yes, condition is intermittent. If no, go to next step.
  4. Remove coil wire from distributor cap. Insert (J 26792) into coil wire and clamp tester onto a ground. Crank engine. Does spark occur? If yes, go to step  13. If no, go to next step.
  5. Measure coil wire resistance. Does resistance measure approximately 1000 ohms/inch? If yes, go to next step. If no, go to step  32.
  6. Disconnect ignition coil harness connector. Probe harness ignition coil driver circuit with test light connected to battery positive voltage. Crank engine. Does test light flash while cranking engine? If yes, go to step  8. If no, go to next step.
  7. Turn OFF the ignition. Probe harness ignition coil driver circuit with test light connected to battery positive voltage. Does test light illuminate? If yes, go to step  29. If no, go to step  9.
  8. Turn ON the ignition, with the engine OFF. Measure coil Ignition 1 voltage with DMM connected to a ground. Does voltage measure above 10 volts? If yes, go to step  22. If no, go to step  18.
  9. Turn OFF the ignition. Check for an open circuit between ignition coil and ICM. Did you find the condition? If yes, go to step  28. If no, go to next step.
  10. Turn ON the ignition, with the engine OFF. Measure Ignition 1 voltage at ICM harness connector with DMM connected to a ground. Does voltage measure above 10 volts? If yes, go to next step. If no, go to step  20.
  11. Probe ICM harness connector ground circuit with test light connected to battery voltage. Does test light illuminate? If yes, go to next step. If no, go to step  24.
  12. Probe IC timing Control circuit with DMM set to AC scale connected to a ground. Crank engine. Observe voltage while engine is being cranked. Does voltage measure 1-4 volts? If yes, go to step  21. If no, go to step  15.
  13. Remove distributor cap. Check cap for the following conditions:
    • Cracks.
    • Moisture.
    • Carbon tracks.
    • Physical damage.

    Did you find any of these conditions? If yes, go to step  34. If no, go to next step.

  14. Crank engine. Observe distributor rotor while engine is being cranked. Did rotor turn? If yes, go to step  33. If no, repair engine mechanical problem. See appropriate article in ENGINES.
  15. Turn OFF the ignition. Disconnect PCM. Check ignition timing Control circuit for an open between PCM and ICM. Did you find the condition? If yes, go to step  25. If no, go to next step.
  16. Probe ignition timing Control circuit at PCM with test light connected to battery voltage. Does test light illuminate? If yes, go to step  26. If no, go to next step.
  17. Turn ON the ignition, with the engine OFF. Probe ignition timing Control circuit at PCM with test light connected to ground. Does test light illuminate? If yes, go to step  27. If no, go to step  23.
  18. Check for an open or shorted to ground Ignition 1 voltage circuit at ignition coil. Repair as necessary. After repairs, go to step  37.
  19. Check for a short to ground on CKP or CMP 12-volt reference circuit. Repair as necessary. Did you find and correct the condition? If yes, go to step  37. If no, go to step  36.
  20. Check for an open or a short to ground on Ignition 1 voltage circuit at ICM. Repair as necessary. After repairs, go to step  37.
  21. Check for poor ICM connection. Did you find a problem? If yes, go to step  30. If no, go to step  35.
  22. Check for poor coil connection. Did you find a problem? If yes, go to step  30. If no, go to step  31.
  23. Check for poor PCM connection. Did you find a problem? If yes, go to step  30. If no, go to step  30.
  24. Repair open ICM ground circuit. After repairs, go to step  37.
  25. Repair open ignition timing Control circuit. After repairs, go to step  37.
  26. Repair grounded ignition timing Control circuit. After repairs, go to step  37.
  27. Repair short to voltage in ignition timing Control circuit. After repairs, go to step  37.
  28. Repair open in coil driver circuit between ignition coil and ICM. After repairs, go to step  37.
  29. Repair short to ground in coil driver circuit between ignition coil and ICM. After repairs, go to step  37.
  30. Repair circuit as necessary. After repairs, go to step  37.
  31. Replace ignition coil. After repairs, go to step  37.
  32. Replace coil wire. After repairs, go to step  37.
  33. Replace distributor rotor. After repairs, go to step  37.
  34. Replace distributor cap. After repairs, go to step  37.
  35. Replace ICM. After repairs, go to step  37.
  36. Replace PCM. Program replacement PCM. See PROGRAMMING in appropriate SELF-DIAGNOSTICS article. After repairs, go to next step.
  37. Operate vehicle within conditions under which original symptom was noted. Does system now operate properly? If yes, system is okay. If no, go to step  1.
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