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HOMESERVICE MANUALSOLDSMOBILE2004BRAVADA AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 114 (ENGINE CONTROLS SELF-DIAGNOSTICS - 2.2L CNG)SELF-DIAGNOSTIC SYSTEMDIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLSDIAGNOSTIC PROCEDURE
2004 Oldsmobile Bravada AWD

Diagnostic Procedure

2004 Oldsmobile Bravada AWDSECTION Diagnostic Procedure
WARNING: This page is about a different car, the 2002 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Install a scan tool. Does the scan tool turn ON? If yes, go to next step. If no, see SCAN TOOL DOES NOT POWER UP in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  2. Using scan tool, attempt to communicate with Alternative Fuels Engine Control Module (AF ECM). Does the scan tool communicate with the module? If yes, go to next step. If no, go to IGNITION RELAY DIAGNOSIS (CAVALIER - CNG) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - CARS - EXCEPT METRO & PRIZM article.
  3. Attempt to establish communication with the BCM, EBCM, IPC, PCM, SDM and VTD modules. If you are using a Tech 2 scan tool, obtain the information with the Class 2 Message Monitor feature. Does the scan tool communicate with all the control modules? If yes, go to next step. If no, see SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT.
  4. Attempt to start engine. Does engine start and idle? If yes, go to step  6 . If no, go to next step.
  5. Remove the CNG 20-amp fuse. Attempt to start engine. Does engine start and idle? If yes, go to IGNITION RELAY DIAGNOSIS (CAVALIER - CNG) under IGNITION SYSTEMS in SYSTEM & COMPONENT TESTING - CARS - EXCEPT METRO & PRIZM article. If no, go to ENGINE CRANKS BUT DOES NOT RUN in appropriate TROUBLE SHOOTING NO-CODES article.
  6. Select the DTC display function for the AF ECM, BCM, EBCM, IPC, PCM, SDM and VTD. Does scan tool display any DTCs? If yes, go to next step. If no, go to step  12 .
  7. With a scan tool, select Captured Info in order to store the powertrain DTC information. When complete, go to next step.
  8. Does the scan tool display DTCs which begin with a "U"? If yes, go to SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE in appropriate BODY CONTROL MODULES article in ACCESSORIES & EQUIPMENT. If no, go to next step.
  9. Were any of the PCM DTCs P0601, P0602 or P1621 set? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  10. Does the scan tool display DTC P0562, P0563, P0621 or P0622? If yes, diagnose affected DTC(s). See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  11. Compare the stored PCM DTCs to the stored AF ECM DTCs. Diagnose the DTCs in the following order: If the same DTC is stored in PCM and AF ECM, refer to the alternative fuels DTC information. If a DTC is stored only in the PCM, refer to the applicable gasoline DTC information. If different DTCs are stored in PCM and AF ECM, diagnose PCM DTCs first. Does scan tool display any PCM or alternative fuels DTCs? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no, go to next step.
  12. Observe the AFO Enable Output and Input data display with the scan tool. Do both parameters display AF ECM? If yes, go to next step. If no, go to FUEL SYSTEM UNWANTED SWITCH TO GASOLINE under FUEL SYSTEMS (2.2L - CAVALIER CNG) in SYSTEM & COMPONENT TESTING - CARS - EXCEPT METRO & PRIZM article.
  13. Observe the Fuel Indicator Light (FIL). Is the FIL illuminated? If yes, diagnose FIL light. See appropriate ANALOG INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If no, go to next step.
  14. Is customer's concern with the transmission? If yes, see appropriate DIAGNOSIS article in AUTOMATIC TRANSMISSIONS. If no, go to next step.
  15. Is the customer's concern with the Inspection/Maintenance (I/M) testing? If yes, go to INSPECTION/MAINTENANCE SYSTEM CHECK  . If no, go to next step.
  16. Turn ignition off. Remove the CNG 20-amp fuse. Attempt to start engine. Does engine start and idle? If yes, go to next step. If no, go to FUEL PUMP RELAY DIAGNOSIS under FUEL SYSTEMS (2.2L - CAVALIER CNG) in SYSTEM & COMPONENT TESTING - CARS - EXCEPT METRO & PRIZM article.
  17. If the customer's concern is a symptom, refer to appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Repair as necessary. Did you complete the action? If yes, system is okay. If no, problem is intermittent. Refer to INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
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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.