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Diagnostic Procedures

WARNING: This page is about a different car, the 2003 Pontiac Sunfire, 2003 Pontiac Grand Am, 2003 Oldsmobile Alero, and 2003 Chevrolet Cavalier. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check - engine controls. See DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check - engine controls, go to next step.
  2. Inspect the EVAP system for the following conditions:
    • A damaged EVAP vent solenoid.
    • A pinched EVAP vent hose.
    • A damaged EVAP canister.
    Did you find and correct the condition? If yes, go to step  17. If no, go to next step.
  3. Turn ignition switch to OFF position. Disconnect the EVAP purge line from the EVAP purge solenoid. Turn ignition switch to RUN position, engine OFF. Is the Fuel Tank Pressure (FTP) sensor parameter -1 to 1 in. H2O? If yes, go to next step. If no, go to step  10.
    4. NOTE: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  4. Turn ignition switch to OFF position. Connect the EVAP purge pipe. Connect the Evaporative Emissions System Tester (EEST) (J 41413-200), or equivalent, power supply clips to a known good 12-volt source. Install the Fuel Fill Cap Adapter (J 41415-40) to the fuel fill pipe. Connect the fuel fill cap to the fuel fill cap adapter. Connect the EEST nitrogen/smoke supply hose to the fuel fill cap adapter. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid closed using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to NITROGEN. Use the remote switch to pressurize the EVAP system to 5 in. H2O. Observe the FTP sensor parameter using a scan tool. Command the EVAP vent solenoid open. Is the FTP Sensor parameter less than 1 in. H2O? If yes, go to DIAGNOSTIC AIDS . If no, go to next step.
  5. Command the EVAP vent solenoid ON and OFF using a scan tool. Do you hear or feel the EVAP vent solenoid click when commanded ON and OFF? If yes, go to next step. If no, go to step  8.
  6. Disconnect the EVAP vent hose from the EVAP vent solenoid. Is the FTP sensor parameter less than 1 in. H2O? If yes, go to step  12. If no, go to next step.
  7. Disconnect the EVAP vent hose from the EVAP canister. Is the FTP sensor parameter less than 1 in. H2O? If yes, go to step  14. If no, go to step  13.
  8. Disconnect the EVAP vent solenoid. Probe the control circuit of the EVAP vent solenoid using a test light connected to battery voltage. Does the test light illuminate? If yes, go to next step. If no, go to step  12.
  9. Check the EVAP vent solenoid control circuit for a short to ground. Did you find and correct the condition? If yes, go to  17. If no, go to step  15.
  10. Check for an intermittent and for a poor connection at the FTP sensor. Did you find and correct the condition? If yes, go to  17. If no, go to step  15.
  11. Check for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to  17. If no, go to step  16.
  12. Replace the EVAP vent solenoid. After repair, go to step  17.
  13. Replace the EVAP canister. After repair, go to step  17.
  14. Repair the pinched or restricted EVAP vent hose. After repair, go to step  17.
  15. Replace the FTP sensor. After repair, go to step  17.
  16. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE REPROGRAMMING  under PROGRAMMING. After replacing PCM, go to next step.
    17. NOTE: Do not exceed the specified value in this step. Exceeding the specified value may produce incorrect test results.
  17. Turn ignition switch to RUN position. Connect all disconnected components. Connect the EEST to the fuel fill pipe. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid closed using a scan tool. Turn the nitrogen/smoke valve on the EEST control panel to NITROGEN. Use the remote switch to pressurize the EVAP system to 5 in. H2O. Observe the FUEL TANK PRESSURE SENSOR parameter using a scan tool. Command the EVAP vent solenoid open using a scan tool. Is the FTP sensor parameter less than zero in. H2O? If yes, go to next step. If no, go to step  2.
  18. Using a scan tool, observe the CAPTURE INFO. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay at this time.
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