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Home >> GMC >> 2003 >> Safari Van Cargo, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 123 (Engine Controls - Self-Diagnostics - 4.0L) >> Diagnostic Tests >> DTC P0449: EVAP Canister Vent Solenoid Control Circuit >> Diagnostic Procedures

Diagnostic Procedures

WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Did you perform the Diagnostic System Check - Engine Controls? If yes, go to next step. If no, go to DIAGNOSTIC SYSTEM CHECK - ENGINE CONTROLS  under SELF-DIAGNOSTIC SYSTEM.
  2. Turn ignition on. Using scan tool, command 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. Using scan tool, observe FREEZE FRAME and/or FAILURE RECORDS data for this DTC. Turn ignition off for 30 seconds. Start engine. Operate vehicle within Conditions for Running DTC or as close to FREEZE FRAME and/or FAILURE RECORDS data as possible. Does this DTC fail this ignition cycle? If yes, go to next step. If no, fault may be intermittent. See INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.
  4. Turn ignition off. Disconnect EVAP vent valve connector. Turn ignition on. Using a test lamp connected to ground, probe Pink wire at EVAP vent valve harness connector. Does the test lamp illuminate? If yes, go to next step. If no, go to step  11.
  5. Connect a test lamp between Pink and White wires at EVAP vent valve harness connector. Using scan tool, command EVAP vent valve ON and OFF. Does the test lamp turn ON or OFF with each command? If yes, go to step  9. If no, go to next step.
  6. Does the test lamp remain illuminated with each command? If yes, go to step  8. If no, go to next step.
  7. Test the control circuit of the EVAP vent solenoid for a short to voltage or an open. Did you find and correct the condition? If yes, go to step  14. If no, go to step  10.
  8. Test the control circuit of the EVAP vent valve 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. Check for poor connections at EVAP vent valve connector. Did you find and correct the condition? If yes, go to step  14. If no, go to step  12.
  10. Check for poor connections at PCM connectors. Did you find and correct the condition? If yes, go to step  14. If no, go to step  13.
  11. Repair EVAP vent valve ignition voltage circuit for open or a short to ground. After repairs, go to step  14.
  12. Replace EVAP canister vent valve. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. After repairs, go to step  14.
  13. Replace the PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Reprogram PCM. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After repairs, go to next step.
  14. Use the scan tool in order to clear the DTCs. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running DTC. Does the DTC run and pass? If yes, go to next step. If no, go to step  2.
  15. With a scan tool, observe the stored information, 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.
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