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Home >> Chevrolet >> 2001 >> Venture Base, Van Passenger >> Repair and Diagnosis (Single Page) >> Engine Performance >> Testing & Diagnosis >> Engine Controls Self-Diagnostics >> Diagnostic Tests >> DTC P0446: Evaporative Emission Vent System Performance ("A" & "B" Series) >> Diagnostic Procedures

Diagnostic Procedures

  1. Perform powertrain diagnostic system check. See POWERTRAIN DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing diagnostic system check, go to next step.
  2. Using scan tool, recheck for DTCs. If DTC P0443, P0449, P0452 or P0453 is set, diagnose affected DTCs first. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If DTC P0443, P0449, P0452 or P0453 is not set, go to next step.
  3. Check for damaged EVAP vent solenoid or pinched EVAP vent hose. Repair as necessary. After repairs, go to step  14. If no problem is found, go to next step.
  4. Disconnect EVAP purge valve purge line. Turn ignition on, with engine off. Observe Fuel Tank Pressure (FTP) parameter on scan tool. If scan tool indicates that FTP parameter is about zero in. H2O, go to next step. If scan tool does not indicate that FTP parameter is about zero in. H2O, go to step  8.
  5. Turn ignition off. Reconnect all previously disconnected hardware. Install Fuel Fill Cap Adapter (J-41415). Connect EVAP Pressure/Purge Diagnostic Station (J-41413) and fuel filler cap to fuel fill cap adapter. Turn ignition on, with engine off. Using scan tool, command EVAP canister vent valve on. DO NOT exceed the specified value in this step or test results will be incorrect. Pressurize EVAP system to 5 in. H2O using EVAP pressure/purge diagnostic station. Rotate rotary switch to OFF/HOLD position. Using scan tool, command EVAP canister vent valve off. If scan tool indicates that FTP parameter is about zero in. H2O, see DIAGNOSTIC AIDS . If scan tool does not indicate that FTP parameter is about zero H2O, go to next step.
  6. Disconnect EVAP canister vent hose from EVAP canister vent valve. If scan tool indicates that fuel tank pressure is within -0.5 to 0.5 in. H2O, go to step  10. If scan tool does not indicate that fuel tank pressure is within -0.5 to 0.5 in. H2O, go to next step.
  7. Disconnect EVAP vapor vent pipe from EVAP canister. If scan tool indicates fuel tank pressure parameter is about zero in. H2O, go to step  13. If scan tool does not indicate fuel tank pressure parameter is about zero in. H2O, go to step  11.
  8. Using scan tool, observe FTP sensor voltage. If FTP sensor voltage is greater than 4.3 volts, go to DTC P0453 . If FTP sensor voltage is not greater than 4.3 volts, go to next step.
  9. Check for poor connections at FTP sensor harness connector. Repair as necessary. After repairs, go to step  14. If connections are okay, go to step  12.
  10. Replace EVAP canister vent valve. After replacing canister vent valve, go to step  14.
  11. Replace EVAP canister. After replacing canister, go to step  14.
  12. Replace FTP sensor. After replacing sensor, go to step  14.
  13. Repair blockage in EVAP vent hose. After repairs, go to next step.
  14. Turn ignition on, with engine off. Using scan tool, command EVAP canister vent valve on. DO NOT exceed 5 in. H2O in this step. Using EVAP diagnostic station, pressurize EVAP system to 5 in. H2O. Turn rotary valve to OFF/HOLD position. Monitor pressure gage on diagnostic station. Using scan tool, command EVAP canister vent valve off. If EVAP system pressure decreases, go to next step. If EVAP system pressure does not decrease, go to step  3.
  15. Using scan tool, select REVIEW INFO option. If any undiagnosed DTCs are displayed, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no DTCs are displayed, system is okay.
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