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Home >> Cadillac >> 2003 >> CTS Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Basic Diagnostic Procedures >> Ignition Systems >> Electronic Ignition System Diagnosis >> Diagnostic Procedure
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Diagnostic Procedure

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 - 3.2L CTS article.
  2. Attempt to start engine. If engine starts and idles, go to next step. If engine does not start and idle, go to step  14.
  3. Idle the engine. Monitor the misfire counters using a scan tool. If the misfire counter increments for one complete bank, go to next step. If misfire counter does not increment for one complete bank, go to step  6.
  4. Turn ignition OFF. Disconnect the electrical connector for the affected electronic ignition module. Probe the electronic ignition module ground circuit with a test light connected to battery positive. If the test light illuminates, go to next step. If the test light does not illuminate, go to step  13.
  5. Turn ignition ON. Probe the electronic ignition module ignition voltage circuit with a test light connected to ground. If the test light illuminates, go to next step. If the test light does not illuminate, go to step  14.
  6. Turn ignition OFF. Remove the affected electronic ignition module from the engine. See ELECTRONIC IGNITION MODULES under IGNITION SYSTEMS in REMOVAL & INSTALLATION article. Leave the electrical connector connected. Disconnect the fuel injector harness multi-connector. Install Spark Tester into one coil or the affected coil of the cylinder, if known. Connect a scan tool. Turn ignition ON, with engine OFF. Operate the affected ignition coil using a scan tool. Repeat for the remaining cylinders. If the Spark Tester show spark on all cylinders, go to step  19. If the Spark Tester does not show spark on all cylinders, go to next step.
  7. Turn ignition OFF. Disconnect the coil pack. Set a Digital Volt-Ohmmeter (DVOM) to the diode test function. Probe the electronic ignition module ground circuit with the Black test lead, and the inside of the spark plug boot with the Red test lead. Repeat this test on the remaining coils. Reverse the test leads and repeat the test. If the DVOM shows continuity on the first test and infinite resistance on the second test, go to next step. If the DVOM shows continuity on the second test, go to step  15.
  8. Set the DVOM to measure resistance. Connect one lead of the DVOM to the electronic ignition module ignition 1 voltage circuit. Check the individual electronic ignition module circuits at the coil pack with the other lead. If the resistance reading is within 0.38-0.86 ohms, go to next step. If the resistance reading is not within 0.38-0.86 ohms, go to step  15.
    9. NOTE: DO NOT substitute a standard test light for the TBI Harness Test Light. The impedance of the TBI Harness Test Light is close to that of the ignition coil. The use of a standard test light may produce inaccurate results.
  9. Turn ignition OFF. Disconnect the electronic ignition module electrical connector on the affected coil. Connect the TBI Harness Test Light between the supply voltage circuit and the control circuit of the affected cylinder with the test adapter leads. Turn ignition ON. If the TBI Harness Test Light illuminates, go to step  11. If the TBI Harness Test Light does not illuminate, go to next step.
  10. Enable the coil for the affected cylinder with the scan tool OUTPUT CONTROL function. If the TBI Harness Test Light flashes ON and OFF, go to step  15. If the TBI Harness Test Light does not flash ON and OFF, go to  12.
  11. Turn ignition OFF. Disconnect the ECM electrical connector C1. Turn ignition ON. If the TBI Harness Test Light is OFF, go to step  17. If the TBI Harness Test Light is ON, go to step  16.
    12. NOTE: A short to voltage on the coil control circuit may cause damage to the ECM.
  12. Test the affected control circuit for an open or a short to voltage. Repair the circuit as necessary. Did you find and correct and open or short to voltage? If yes, go to step  21. If no, go to step  17.
  13. Repair the open in the ground circuit. After repairs are complete, go to step  21.
  14. Repair the open or short to ground in the ignition 1 voltage circuit. Replace the fuse if the ignition 1 voltage circuit is shorted to ground. After repairs are complete, go to step  21.
  15. Replace the electronic ignition module. See ELECTRONIC IGNITION MODULES under IGNITION SYSTEMS in REMOVAL & INSTALLATION article. After repairs are complete, go to step  21.
    16. NOTE: A short to ground on a coil control circuit may damage the ignition coil.
  16. Repair the short to ground in the control circuit. After repairs are complete, go to step  21.
  17. Inspect for a faulty connection or a faulty terminal tension at the ECM harness connector. Repair as necessary. Did you find and correct a fault connection? If yes, go to step  21. If no, go to next step.
    18. NOTE: Perform the idle learn procedure when replacing the ECM or the throttle body.
  18. Replace ECM. See ENGINE CONTROL MODULE under COMPUTERIZED ENGINE CONTROLS in REMOVAL & INSTALLATION - CTS article. After repairs are complete, go to step  21.
  19. Inspect the system for the following conditions that may be related to a misfire:
    • Fouled spark plugs caused by the fuel system compensating for a misfiring cylinder.
    • Water intrusion or contamination around the electronic ignition module.
    • Secondary ignition leakage around the base, tower and the boot of the coil.

    Did you find and correct the condition? If yes, go to step  21. If no, go to next step.

  20. Inspect the spark plugs for the proper gap or for signs of damage. Replace the spark plugs, as necessary. See SPARK PLUGS under IGNITION SYSTEMS in REMOVAL & INSTALLATION - CTS article. After repairs are complete, go to next step.
  21. Start and idle the engine. Monitor the misfire counters using the scan tool. If any of the misfire counters increment, go to step  2. If misfire counters do not increment, go to next step.
  22. Using a scan tool, observe the stored information, CAPTURE INFO. If the scan tool displays any DTC's that you have not diagnosed, see DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF DIAGNOSTICS - 3.2L CTS article. If no DTC's are displayed, system is okay.
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