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HOMESERVICE MANUALSCHEVROLET2002SILVERADO 1500 HD, RWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 72 (ENGINE CONTROLS SELF-DIAGNOSTICS - 2.2L)DIAGNOSTIC TESTSDTC P0446: EVAP VENT SYSTEM PERFORMANCEDIAGNOSTIC PROCEDURES
2002 Chevrolet Silverado 1500 HD, RWD

Diagnostic Procedures

2002 Chevrolet Silverado 1500 HD, RWDSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 2002 GMC Sonoma and 2002 Chevrolet S10 Pickup. 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, go to next step.
  2. Did DTC P0452 or P0453 also set? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, go to next step.
  3. Check EVAP system for damaged EVAP vent valve or pinched EVAP vent hose. Did you find and correct the condition? If yes, go to step  19. If no, go to next step.
  4. Install Fuel Tank Cap Adapter (J-41415-40) to fuel filler neck. Install EVAP Pressure/Purge Diagnostic Station (J-41413) to fuel tank cap to adapter. Turn ignition on, with engine off. Using scan tool, command the vent valve on (closed). Using diagnostic station, pressurize EVAP system to 13 in. H2O. Rotate rotary switch to OFF/HOLD position. Compare Fuel Tank Pressure (FTP) sensor value between scan tool and diagnostic station gauge reading. Are the EVAP pressure/purge diagnostic station gauge and the scan tool FTP sensor values similar? If yes, go to next step. If no, go to step  9.
  5. Monitor EVAP pressure/purge diagnostic station gauge. Command EVAP canister vent valve off (open). Did the EVAP pressure/purge diagnostic station gauge drop quickly to near the specified value? If yes, problem is intermittent. If no, go to next step.
  6. Using scan tool, command EVAP vent valve on and off. Do you hear or feel the EVAP vent valve click when commanded ON and OFF? If yes, go to next step. If no, go to step  10.
  7. Turn ignition off. Reconnect all previously disconnected hardware. Turn ignition on, with engine off. Using scan tool, command EVAP vent valve on. Using diagnostic station, pressurize EVAP system to 13 in. H2O. Rotate rotary switch to OFF/HOLD position. Disconnect EVAP vent hose from EVAP vent valve. Does the scan tool indicate FTP about zero in. H2O? If yes, go to step  14. If no, go to next step.
  8. Disconnect EVAP vent hose from EVAP canister. Does the scan tool indicate FTP about zero in. H2O? If yes, go to step  16. If no, go to step  15.
  9. Does the scan tool indicate FTP sensor voltage is greater than 4.3 volts? If yes, go to DTC P0453: FUEL TANK PRESSURE SENSOR CIRCUIT - HIGH VOLTAGE . If no, go to step  12.
  10. Disconnect the EVAP vent valve harness connector. Probe the EVAP vent valve control circuit with a test light connected to a B+. Does the test light illuminate? If yes, go to next step. If no, go to step  14.
  11. 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  19. If no, go to step  13.
  12. Test for poor connections at the harness connector of the FTP. Did you find and correct the condition? If yes, go to step  19. If no, go to step  17.
  13. Check for poor connections at PCM harness connector. Did you find and correct the condition? If yes, go to step  19. If no, go to step  18.
  14. Replace EVAP vent valve. After replacing vent valve, go to step  19.
  15. Replace EVAP canister. After replacing canister, go to step  19.
  16. Repair blockage in EVAP vent hose. After repairs, go to step  19.
  17. Replace FTP sensor. After replacing sensor, go to step  19.
  18. Replace PCM. See appropriate REMOVAL, OVERHAUL & INSTALLATION article. Perform PCM relearn procedure. See POWERTRAIN CONTROL MODULE  under PROGRAMMING. After replacing PCM, go to next step.
  19. Reconnect all EVAP hardware that was previously disconnected. Turn ignition on, with engine off. Using scan tool, command EVAP canister vent valve on (closed). Using diagnostic station, pressurize EVAP system to 13 in. H2O. Rotate rotary switch to OFF/HOLD position. Command EVAP canister vent valve off (open). Is the EVAP pressure/purge diagnostic station value about zero in. H2O? If yes, go to next step. If no, go to step  3.
  20. Using scan tool, observe stored information and capture information. Does the scan tool display any DTCs that you have not diagnosed? If yes, diagnose affected DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . If no, system is okay.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.