LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 378 (Engine Controls Self-Diagnostics - 3.1L Engine) >> Diagnostic Tests >> DTC P0449: EVAP Vent Solenoid Control Circuit >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2003 Pontiac Grand Prix, 2003 Chevrolet Malibu, and 2003 Buick Century. 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. Turn ignition switch to RUN position, engine OFF. Command the EVAP vent solenoid ON and OFF using the scan tool. Do you hear or feel a click from the EVAP vent solenoid when commanded ON and OFF? If yes, go to next step. If no, go to step  4.
  3. Observe the Freeze Frame/Failure Records for this DTC. Turn ignition switch to OFF position for 30 seconds. Turn ignition switch to RUN position, engine OFF. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to next step. If no, go to INTERMITTENTS in TROUBLE SHOOTING - 3.1L CENTURY, GRAND PRIX & MALIBU article.
  4. Turn ignition switch to OFF position. Disconnect the EVAP vent solenoid. Turn ignition switch to RUN position, engine OFF. Probe the EVAP vent solenoid ignition 1 voltage circuit using a test light 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 solenoid and the ignition 1 voltage circuit of the EVAP vent solenoid. Command the EVAP vent valve ON and OFF using a scan tool. Does the test light turn ON or 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  13.
  10. Test for an intermittent and for a poor connection at the PCM. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair the open or short to ground in the ignition 1 voltage circuit. Replace the fuse if necessary. After repair, go to step  14.
  12. Replace the EVAP vent solenoid. After repair, go to step  14.
  13. Replace PCM. See POWERTRAIN CONTROL MODULE in appropriate REMOVAL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  14. Clear the DTCs using a scan tool. Turn ignition switch to OFF position for 30 seconds. Start the engine. Operate the vehicle within the Conditions For Running Test. See CONDITIONS FOR RUNNING TEST . You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition? If yes, go to step  2. If no, go to next step.
  15. Using the scan tool, observe the stored information in 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.
scientia non olet · About LEMON Manuals