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HOMESERVICE MANUALSOLDSMOBILE2004BRAVADA AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 443 (ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES - 3.8L)IGNITION SYSTEMSELECTRONIC IGNITION SYSTEM DIAGNOSISDIAGNOSTIC PROCEDURE
2004 Oldsmobile Bravada AWD

Diagnostic Procedure

2004 Oldsmobile Bravada AWDSECTION Diagnostic Procedure
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Pontiac Grand Prix, 2003 Pontiac Bonneville, 2003 Chevrolet Monte Carlo, 2003 Chevrolet Impala, and 2003 Buick Regal. However, it is still accessible from the selected car via links, so may be relevant.
  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 - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article.
    2. NOTE: Before proceeding with this diagnostic procedure, verify that the vehicle's battery is fully charged.
  2. Check the fuses which supply ignition 1 voltage to the Ignition Control Module (ICM) and the Powertrain Control Module (PCM). Are either of the fuses open? If yes, go to step  27. If no, go to next step.
  3. Turn ignition switch to RUN position, engine OFF. Crank the engine. Observe the engine RPM parameter using a scan tool. Does the scan tool display engine RPM? If yes, go to step  13. If no, go to next step.
  4. Turn ignition switch to OFF position. Disconnect the ICM. Turn ignition switch to RUN position, engine OFF. Connect a test light between the ICM ignition 1 voltage circuit and the ICM ground circuit. Does the test light illuminate? If yes, go to step  6. If no, go to next step.
  5. Leave the ICM disconnected. Connect the test light between the ICM ignition 1 voltage and a good ground. Does the test light illuminate? If yes, go to step  28. If no, go to step  29.
  6. Turn ignition switch to OFF position. Reconnect the ICM. Disconnect the Crankshaft Position (CKP) sensor harness connector. Turn ignition switch to RUN position, engine OFF. Connect a DVOM between the CKP sensor 12-volt reference circuit and the CKP sensor ground circuit. Is the difference between the measured voltage and the system voltage more than 0.5 volt? If yes, go to step  8. If no, go to next step.
  7. Connect the DVOM between the CKP sensor 1 signal circuit and the CKP sensor ground circuit. Is the voltage 6-8 volts? If yes, go to step  16. If no, go to step  11.
  8. Connect the DVOM between the CKP sensor 12-volt reference circuit and a good ground. Is the difference between the measured voltage and the system voltage more than 0.5 volt? If yes, go to next step. If no, go to step  10.
  9. Turn ignition switch to OFF position. Leave the CKP sensor disconnected. Disconnect the ICM harness connector. Check the CKP sensor ground circuit for an open. Did you find and correct the condition? If yes, go to step  33. If no, go to step  27.
  10. Turn ignition switch to OFF position. Leave the CKP sensor disconnected. Disconnect the ICM harness connector. Check the CKP 12-volt reference circuit for an open and for a short to ground. Did you find and correct the condition? If yes, go to step  35. If no, go to step  26.
  11. Leave the DVOM connected. Turn ignition switch to OFF position. Disconnect the ICM harness connector. Turn ignition switch to RUN position, engine OFF. Is the difference between the measured voltage and the system voltage more than 0.5 volt? If yes, go to step  30. If no, go to next step.
  12. Check the CKP sensor 1 signal circuit for an open or a short to ground. Did you find and correct the condition? If yes, go to step  35. If no, go to step  26.
  13. Turn ignition switch to OFF position. Disconnect a spark plug wire from a spark plug. Install Spark Tester (J 26792), or equivalent, in the end of the spark plug wire. Jump the companion cylinder's ignition wire to a good ground. The companion cylinder is the cylinder that shares the same ignition coil. Crank the engine while observing the spark. Repeat the above test for each ignition wire, noting any cylinders that do not have spark. Do all of the cylinders have spark? If yes, go to step  23. If no, go to next step.
  14. Do any of the cylinders have spark? If yes, go to step  19. If no, go to next step.
  15. Turn ignition switch to OFF position. Disconnect the CKP sensor harness connector. Turn ignition switch to RUN position, engine OFF. Connect the DVOM between the CKP sensor 2 signal circuit and a good ground. Is the measured voltage 6-8 volts? If yes, go to next step. If no, go to step  17.
  16. Check for intermittent and for a poor connection at the CKP sensor. Did you find and correct the condition? If yes, go to step  35. If no, go to step  32.
  17. Turn ignition switch to OFF position. Disconnect the ICM harness connector. Turn ignition switch to RUN position, engine OFF. Check the CKP sensor 2 signal circuit for a short to voltage or a short to the sensor 12-volt reference circuit. Did you find and correct the condition? If yes, go to step  35. If no, go to next step.
  18. Check the CKP sensor 2 signal for a short to ground or an open. Did you find and correct the condition? If yes, go to step  35. If no, go to step  26.
    19. NOTE: If carbon tracking is detected on any component, replace that component and the mate.
  19. Check the ignition coils and the ignition wires associated with the cylinders that did not have spark. Verify that the ignition components are free of cracks and carbon tracking. Replace any damaged ignition components. Did you find and correct the condition? If yes go to step  35. If no, go to next step.
  20. Measure the ignition coils secondary resistance. Is the resistance 5-8 k/ohms? If yes, go to next step. If no, go to step  34.
  21. Measure the resistance of the ignition wires associated with the cylinders that did not have spark. Is the resistance more than 3 k/ohms per foot? If yes, go to step  31. If no, go to next step.
  22. Remove the coils associated with the cylinder that did not have spark. Connect a test light across the ignition module primary circuit, between the ICM terminals, for the coils. Observe the test light while cranking the engine. Does the test light flash continuously while the engine is being cranked? If yes, go to step  34. If no, go to step  33.
  23. Remove the spark plugs from all of the cylinders. Check the spark plug electrodes. Are any of the spark plugs fouled? If yes, check engine compression. See CYLINDER COMPRESSION PRESSURE  under MECHANICAL INSPECTION.
  24. Check for a short between the ICM CKP sensor 1 and CKP sensor 2 circuits. Did you find and correct the condition? If yes, go to step  35. If no, go to next step.
  25. Check for a short between the medium resolution and low resolution speed signal circuits to the PCM. Did you find and correct the condition? If yes, go to step  35. If no, check engine compression. See CYLINDER COMPRESSION PRESSURE  under MECHANICAL INSPECTION.
  26. Check for an intermittent and for a poor connection at the ICM. Did you find and correct the condition? If yes, go to step  35. If no, go to step  33.
  27. Repair the short to ground in the affected circuit. After repair, go to step  35.
  28. Repair the open in the ICM ground circuit. After repair, go to step  35.
  29. Repair the open in the ignition 1 voltage circuit. After repair, go to step  35.
  30. Repair the short to voltage in the CKP sensor 1 signal circuit. After repair, go to step  35.
  31. Replace the spark plug wires. After repair, go to step  35.
  32. Replace the CKP sensor. After repair, go to step  35.
  33. Replace the ICM. After repair, go to step  35.
  34. Replace the ignition coils associated with the cylinders that did not have spark. After repair, go to next step.
  35. Attempt to start the engine. Does the engine start and continue to run? If yes, go to next step. If no, go to step  2.
  36. Clear the DTCs using a scan tool. Turn ignition switch to OFF position for 30 seconds. Start the engine. Let the engine reach operating temperature. Are there any DTCs that have not been diagnosed? If yes, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS in SELF-DIAGNOSTICS - 3.8L BONNEVILLE, GRAND PRIX, IMPALA, LESABRE, MONTE CARLO, PARK AVENUE & REGAL article. If no, system is okay at this time.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.