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Home >> Pontiac >> 2003 >> Aztek FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0449: EVAP Vent Valve Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, see DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on, with engine off. With the scan tool, command the EVAP vent valve ON and OFF. Do you hear or feel a click from the EVAP vent valve when the valve is commanded ON and OFF? If yes, go to next step. If no, go to step  4.
  3. Review the Freeze Frame/Failure Records data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC or as close to the Freeze Frame/Failure Records data that you observe. See CONDITIONS FOR RUNNING DTC . Does this DTC fail this ignition cycle? If yes, go to next step. If no, see INTERMITTENTS in TROUBLE SHOOTING - NO CODES - 3.4L AZTEK & RENDEZVOUS article.
  4. Turn ignition off. Disconnect the EVAP vent solenoid. Turn ignition on, with engine off. Probe the ignition 1 voltage circuit of the EVAP vent solenoid with a test light that is connected to a good ground. Does the test light illuminate? If yes, go to next step. If no, go to step  11.
  5. Connect a test light between the control circuit of the EVAP vent valve and the ignition voltage circuit of the EVAP vent valve at the body pass-through connector. With a scan tool, command the EVAP vent valve ON and OFF. Does the test light turn ON and OFF with each command? If yes, go to step  9. If no, go to next step.
  6. Does the test light remain illuminated with each command? If yes, go to step  8. If no, go to next step.
  7. Test the control circuit for an open or short to voltage. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test the control circuit for a short to ground. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  9. Test for an intermittent and for a poor connection at the EVAP vent solenoid. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Test for an intermittent and for a poor connection at the control module. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair open or short to ground in the ignition 1 voltage circuit. Replace fuse, if necessary. After repairs, go to step  14.
  12. Replace EVAP vent solenoid. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. After repairs, go to step  14.
  13. Replace PCM. See REMOVAL & INSTALLATION - AZTEC & RENDEZVOUS article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Clear the DTCs with a scan tool. Turn ignition off for 30 seconds. Start engine. Operate the vehicle within the Conditions for Running DTC. See CONDITIONS FOR RUNNING DTC . Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. Observe the stored information, Capture Info with a scan tool. Does the scan tool display any DTCs that you have not diagnosed? If yes, see DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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