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Ignition System

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article. After performing OBD system check, go to next step.
  2. Check Ignition Control Module (ICM) ignition feed circuit fuse and fuel injector ignition feed circuit fuse. If either fuse is blown, locate and repair short to ground in suspect ignition feed circuit. If fuses are okay, go to next step.
  3. Turn ignition off. Install fuel pressure gauge to fitting on fuel rail. Turn ignition on and observe fuel pressure. Fuel pressure should be 48-55 psi (3.4-3.8 kg/cm2 ) and hold steady. If fuel pressure is as specified, go to step  5 . If fuel pressure is not as specified, go to next step.
  4. If fuel pressure is indicated, but not as specified, diagnose fuel system. See BASIC FUEL SYSTEM CHECKS  . If fuel pressure is not present, go to FUEL SYSTEM ELECTRICAL CIRCUIT (VIN K)  or FUEL SYSTEM ELECTRICAL CIRCUIT (VIN 1)  .
  5. Turn ignition off. Remove fuel pressure gauge. Install scan tool. Turn ignition on. Using scan tool, select ENGINE DATA 1. Observe engine RPM while cranking engine. If scan tool indicates engine RPM, go to step  17 . If scan tool does not indicate engine RPM, go to next step.
  6. Turn ignition off. Disconnect Ignition Control Module (ICM) harness connector. Turn ignition on. Connect a test light between ignition positive feed circuit and ground circuit at ICM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step  8 . If test light does not illuminate, go to next step.
  7. Leave ICM harness connector disconnected. Using a test light connected to ground, probe ignition positive feed circuit at ICM harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step  39 . If test light does not illuminate, go to step  40 .
  8. Turn ignition off. Reconnect ICM harness connector. Disconnect 18X Crankshaft Position (CKP) sensor harness connector. Turn ignition on. Using DVOM, measure voltage between 18X CKP sensor feed circuit and CKP sensor ground circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage, go to next step. If voltage is not as specified, go to step  11 .
  9. Measure voltage between 18X CKP sensor signal circuit and CKP sensor ground circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is 6-8 volts, go to next step. If voltage is not as specified, leave DVOM connected and go to step  14 .
  10. Check for poor connections at CKP sensor. Repair as necessary. If connections are okay, go to step  41 .
  11. Measure voltage between engine ground and 18X CKP sensor feed circuit at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is near battery voltage, go to next step. If voltage is not as specified, go to step  13 .
  12. Turn ignition off. Leave CKP sensor harness connector disconnected. Disconnect Ignition Control Module (ICM) harness connector. Check for open in CKP sensor ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If ground circuit is okay, go to step  38 .
  13. Turn ignition off. Leave 18X CKP sensor harness connector disconnected. Disconnect Ignition Control Module (ICM) harness connector. Check 18X CKP sensor feed circuit for an open or short to ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sensor feed circuit is okay, go to step  38 .
  14. Turn ignition on. If DVOM displays battery voltage, go to next step. If voltage is not as specified, go to step  16 .
  15. Locate and repair short to power. See appropriate wiring diagram in WIRING DIAGRAMS article.
  16. Turn ignition off. Check 18X CKP sensor signal circuit for an open, short to chassis ground or short to sensor ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If signal circuit is okay, go to step  38 .
  17. Turn ignition off. Disconnect all fuel injector harness connectors. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector (one at a time). If test light illuminates for any of the injectors, go to next step. If test light does not illuminate for any injector, go to step  19 .
  18. Leave fuel injector harness connectors disconnected. Turn ignition off. Disconnect PCM harness connectors. Turn ignition on. Connect fuel injector test light to each fuel injector harness connector (one at a time). If test light illuminates for any of the injectors, go to step  43 . If test light does not illuminate for any injector, go to step  46 .
  19. Leave fuel injector harness connectors disconnected. Connect fuel injector test light to a fuel injector harness connector and crank engine. Repeat for each fuel injector. If test light flashes for each fuel injector, go to step  24 . If test light does not flash for each fuel injector, go to next step.
  20. If test light flashed for any fuel injector, go to next step. If test light did not flash for any fuel injector, go to step  22 .
  21. Turn ignition off. Leave fuel injector harness connectors disconnected. Disconnect PCM harness connector. Check for an open fuel injector control circuits associated with fuel injector circuit that did not flash test light. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If fuel injector circuits are okay, go to step  44 .
  22. Leave fuel injector harness connectors disconnected. Turn ignition on. Using a test light connected to ground, probe ignition positive feed circuit to each fuel injector. See appropriate wiring diagram in WIRING DIAGRAMS article. If test light illuminates, go to step  44 . If test light does not illuminate, go to next step.
  23. Locate and repair open in ignition positive feed circuit to fuel injector. See appropriate wiring diagram in WIRING DIAGRAMS article.
  24. Turn ignition off. Install Spark Tester (J-26792) to cylinder No. 1, 2 and 3 (one at a time). Connect the spark plug wire of companion cylinder to ground (i.e., 1/4, 2/5, 3/6). Crank engine and observe spark tester. If spark is present at all cylinders, go to step  34 . If spark is not present at all cylinders, go to next step.
  25. If spark is present at any cylinder, go to step  30 . If spark is not present at any cylinder, go to next step.
  26. Turn ignition off. Disconnect 18X CKP sensor harness connector. Turn ignition on. Measure voltage between ground and CKP sync signal at CKP sensor harness connector. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is 6-8 volts, go to next step. If voltage is not as specified, go to step  28 .
  27. Check for poor connections at CKP sensor harness connector. Repair as necessary. If connections are okay, go to step  41 .
  28. Turn ignition off. Disconnect Ignition Control Module (ICM) harness connector. Turn ignition on. Check CKP sensor sync signal circuit for a short to power or short to 18X CKP sensor feed circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sync signal circuit is okay, go to next step.
  29. Turn ignition off. Check CKP sensor sync signal circuit for a short to chassis ground or sensor ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If sync signal circuit is okay, go to step  38 .
  30. Inspect ignition coils and spark plug wires associated with cylinders that did not indicate spark. Repair as necessary. If ignition coils and spark plug wires are okay, go to next step.
  31. Measure ignition coil secondary resistance. If resistance is 5000-8000 ohms, go to next step. If resistance is not as specified, replace ignition coil.
  32. Measure resistance of spark plug wires associated with cylinders that did not indicate spark. If resistance is 1000-1500 ohms per foot, go to next step. If resistance is greater than specified, replace spark plug wires.
  33. Remove ignition coils associated with cylinders that did not indicate spark. Connect a test light across ignition coil primary circuit associated with cylinders that did not indicate spark. See appropriate wiring diagram in WIRING DIAGRAMS article. Crank engine and observe test light. If test light flashes continuously, go to step  45 . If test light does not flash continuously, go to step  42 .
  34. Remove spark plugs from all cylinders. Inspect spark plugs for excessive fouling. If spark plugs are fouled, check engine mechanical condition. Repair as necessary. If spark plugs are okay, go to next step.
  35. Check for the following:
    • Short between 18X CKP and CKP sync signal inputs to ICM.
    • Short between 18X and 3X reference signal inputs to PCM.
    • Stuck TP sensor.
    • Faulty ECT sensor.
    • Unresponsive MAP sensor.
    Repair as necessary. If no problem is found, go to next step.
  36. Test fuel for contamination. Clean fuel system if necessary. If fuel is okay, go to next step.
  37. Check for bent push rods, faulty or incorrect camshaft, leaking or sticky valves or rings, excessive valve deposits, loose or worn rocker arms, weak valve springs, incorrect valve timing or a leaking head gasket. Repair as necessary.
  38. Check for poor connections at ICM harness connector. Repair as necessary. If no problem is found, go to step  42 .
  39. Locate and repair open in ICM ground circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  40. Locate and repair open in ignition positive feed circuit to ICM. See appropriate wiring diagram in WIRING DIAGRAMS article.
  41. Replace 18X CKP sensor.
  42. Replace ICM.
  43. Locate and repair short to ground in fuel injector control circuits associated with test light that remained illuminated. See appropriate wiring diagram in WIRING DIAGRAMS article.
  44. Check for poor connections at PCM. Repair as necessary. If connections are okay, go to step  46 .
  45. Replace ignition coils associated with cylinders that did not indicate spark.
  46. Replace PCM. Perform PCM relearn procedures.
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