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Home >> Chevrolet >> 2000 >> Prizm Base, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls Self-Diagnostics - 1.8L >> Diagnostic Tests >> DTC P0446: EVAP Vent System Performance >> Diagnostic Procedures
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Diagnostic Procedures

  1. Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing OBD system check, go to next step.
  2. Using scan tool, retrieve DTCs. If DTC P0450 is set, diagnose DTC P0450 first. See DTC P0450: EVAPORATIVE EMISSION (EVAP) SYSTEM PRESSURE SENSOR CIRCUIT  . If DTC P0450 is not set, go to next step.
  3. Check the following components for cracks, leaks or damage; fuel tank filler cap, fuel tank pressure sensor, fuel tank, EVAP canister, fuel supply lines, hoses and fittings. Repair as necessary. After repairs, go to step  48 . If components are okay, go to next step.
  4. Disconnect both vacuum hoses from EVAP canister purge valve. Blow air into lower port of EVAP canister purge valve. Air should NOT pass through solenoid and out the upper port. Turn ignition on, with engine off. Using a scan tool, command EVAP canister purge valve on. Blow air into lower port of EVAP canister purge valve. Air should pass through solenoid and out of upper port. If EVAP canister purge valve pass both tests, go to step  9 . If EVAP canister purge valve did not pass both tests, go to next step.
  5. Using a DVOM, check resistance of EVAP canister purge valve. If resistance is less than 27-33 ohms at 68°F (20°C), go to step  42 . If resistance is not less than 27-33 ohms at 68°F (20°C), go to next step.
  6. Disconnect EVAP canister purge valve harness connector. Turn ignition on, with engine off. Using a test light connected to ground, probe ignition positive voltage circuit of EVAP canister purge valve harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  8 .
  7. Turn ignition on, with engine off. Using test light connected to battery voltage, probe control circuit of EVAP canister purge valve in harness connector. Using scan tool, command EVAP canister purge valve on and off while observing test light. If test light illuminate only when EVAP canister purge valve was commanded on, go to step  38 . If test light does not illuminate when EVAP canister purge valve was commanded on, go to step  45 .
  8. Repair open in ignition positive voltage circuit of EVAP canister purge valve. After repairs, go to step  48 .
  9. Loosen fuel tank filler cap in order to release any pressure inside fuel tank. Turn ignition on, with engine off. Using scan tool, observe fuel tank pressure sensor parameter. If fuel tank pressure sensor is 0.0-0.5 in H2O, go to next step. If fuel tank pressure is not 0.0-0.5 in. H2O, go to step  22 .
  10. Disconnect EVAP canister vent valve harness connector. Turn ignition on, with engine off. Using a test light connected to ground, probe EVAP canister vent valve ignition positive voltage circuit at harness connector. If test light illuminates, go to next step. If test light does not illuminate, go to step  13 .
  11. Remove EVAP canister vent valve from air cleaner housing. Disconnect vacuum hose from EVAP canister vent valve. Blow air into lower port of EVAP canister vent valve. Air should pass through solenoid and out the upper port. Using a fused jumper wire, apply battery positive voltage to EVAP canister vent valve terminal No. 2 (Black wire). Connect EVAP canister vent valve terminal No. 1 (Blue/Black wire) to ground. Blow air into lower port of EVAP canister vent valve. Air should not pass through the solenoid and out of the upper port. If EVAP canister vent valve passed both tests, go to next step. If EVAP canister vent valve did not pass both tests, go to step  39 .
  12. Turn ignition on, with engine off. Using a test light connected to battery voltage, probe EVAP canister vent valve control circuit at harness connector. If test light illuminates, go to step  37 . If test light does not illuminate, go to step  14 .
  13. Repair open in EVAP canister vent valve ignition positive voltage circuit. After repairs, go to step  48 .
  14. Check resistance of EVAP canister vent valve. If resistance is 25-30 ohms at 68°F (20°C), go to next step. If resistance is not 25-30 ohms at 68°F (20°C), go to step  39 .
  15. Remove fuel filler cap. Install Gas Cap Adapter (J 41415-30) to fuel filler pipe. Connect the EVAP Pressure/Purge Cart (J 41413 EVAP) to gas cap adapter. Pressurize EVAP system to 4.5-5.5 in. H2O with switch in HOLD position. If EVAP system holds the specified pressure for at least 2 minutes, go to step  17 . If EVAP system does not hold the specified pressure for at least 2 minutes, go to next step.
  16. Check for leak in the EVAP pressure switching solenoid or vacuum hoses connected to EVAP pressure switching solenoid. Repair or replace any components as necessary. After repairs, go to step  48 . If no problem is found, go to step  30 .
  17. Disconnect EVAP pressure switching solenoid harness connector. Turn ignition on, with engine off. Using test light connected to ground, probe EVAP pressure switching solenoid harness connector terminal No. 2 (Black wire). If test light illuminates, go to next step. If test light does not illuminate, go to step  21 .
  18. Remove EVAP pressure switching solenoid. Check EVAP pressure switching solenoid. See appropriate SYSTEM & COMPONENT SYSTEM article. If solenoid is okay, go to next step. If solenoid is not okay, go to step  33 .
  19. Turn ignition on, with engine off. Using test light connected to battery voltage, probe EVAP pressure switching solenoid control circuit at harness connector. If test light illuminates, go to step  37 . If test light does not illuminate, go to next step.
  20. Remove ORVR vent line from EVAP canister and plug hose. Remove EVAP vapor line and purge line to canister purge solenoid from EVAP canister. Connect EVAP vapor line and purge line together using a section of vacuum pipe. Attempt to pressurize EVAP system to 30 in. H2O using EVAP Pressure/Purge Cart (J 41413) and placing knob in HOLD position. Locate any leaks in EVAP and fuel supply systems using Ultrasonic Leak Detector (J 41416). If necessary, lower fuel tank in order to check condition of fill limiter vent valve and rollover valve. Ensure to check fuel sender assembly for a correct seal. If any EVAP or fuel supply system leak is found, go to step  32 . If no EVAP or fuel supply leak is found, go to step  43 .
  21. Repair open in EVAP pressure switching solenoid ignition positive voltage circuit. After repairs, go to step  48 .
  22. Disconnect vapor pressure supply hose to fuel tank pressure sensor. Turn ignition on, with engine off. Observe fuel tank pressure sensor parameter on scan tool. If fuel tank pressure sensor parameter is within 0.0-0.5 in H2O, go to next step. If fuel tank pressure sensor parameter is not within 0.0-0.5 in. H2O, go to step  24 .
  23. Check cause of trapped vapor pressure to FTP sensor. Check for pinched, crushed or restricted vapor line or hose from fuel tank. Check for blocked or restricted vapor pressure passage in fuel tank. Repair as necessary. After repairs, go to step  48 .
  24. Turn ignition off. Disconnect fuel tank pressure sensor harness connector. Turn ignition on, with engine off. Using DVOM, check voltage from harness connector terminal No. 3. If voltage reading is 5 volts, go to next step. If voltage reading is not 5 volts, go to step  26 .
  25. Check voltage on harness connector terminal No. 2. If voltage reading is about 4.9 volts, go to step  28 . If voltage reading is not about 4.9 volts, go to step  27 .
  26. Repair open in reference voltage circuit of fuel tank pressure sensor between sensor and PCM. After repairs, go to step  48 .
  27. Check input circuit of fuel tank pressure sensor for an open or short. Ensure that input circuit is not shorted to sensor ground circuit. Repair as necessary. After repairs, go to step  48 . If circuit is okay, go to step  47 .
  28. Using test light connected to battery voltage, probe sensor harness connector terminal No. 1. If test light illuminates, go to step  36 . If test light does not illuminate, go to next step.
  29. Repair open in fuel tank pressure sensor ground circuit between sensor and PCM. After repairs, go to step  48 .
  30. Remove ORVR vent line from EVAP canister and plug hose. Remove EVAP vapor line from EVAP canister and plug hose. Attempt to pressurize EVAP system to 30 in. H2O using EVAP Pressure/Purge Cart (J 41413) and placing knob in HOLD position. Locate any leaks in EVAP and fuel supply systems using Ultrasonic Leak Detector (J 41416). If necessary, lower fuel tank in order to check condition of fill limiter vent valve and rollover valve. Be sure to check fuel sender assembly for a correct seal. If any EVAP system or fuel supply system leak is found, go to step  32 . If no EVAP system or fuel supply system leak is found, go to next step.
  31. Replace EVAP canister. After replacing canister, go to step  48 .
  32. Repair or replace leaking EVAP system or fuel tank component. After repairs, go to step  48 .
  33. Using DVOM, check resistance of EVAP pressure switching solenoid. If resistance is less than 27 ohms at 68°F (20°C), go to next step. If resistance is not less than 27 ohms at 68°F (20°C), go to step  35 .
  34. Replace EVAP pressure switching solenoid and PCM. Program replacement PCM using required equipment. After replacing solenoid and PCM, go to step  48 .
  35. Replace EVAP pressure switching solenoid. After replacing solenoid, go to step  48 .
  36. Replace fuel tank pressure sensor. After replacing sensor, go to step  48 .
  37. Check solenoid control circuit for a short to ground. Repair as necessary. After repairs, go to step  48 . If circuit is okay, go to step  47 .
  38. Replace EVAP canister purge valve. After replacing purge valve, go to step  48 .
  39. Check resistance of EVAP canister vent valve. If resistance is less than 25-30 ohms at 68°F (20°C), go to next step. If resistance is not less than 25-30 ohms at 68°F (20°C), go to step  41 .
  40. Replace EVAP canister vent valve and PCM. Program replacement PCM using required equipment. After replacing vent valve and PCM, go to step  48 .
  41. Replace EVAP canister vent valve. After replacing vent valve, go to step  48 .
  42. Replace EVAP canister purge valve and PCM. Program replacement PCM using required equipment. After replacing purge valve and PCM, go to step  48 .
  43. Using scan tool, clear DTCs. Place vehicle into Check Mode. Operate vehicle within Freeze Frame conditions or until EVAP purge test is complete. Recheck DTCs. If DTC resets, go to next step. If DTC does not reset, see DIAGNOSTIC AIDS  .
  44. Remove EVAP canister. Visually and physically inspect EVAP canister for cracks or signs of damage. Perform a comprehensive inspection of the EVAP canister. Replace EVAP canister if damaged or fails any inspections. If EVAP canister was replaced, go to step  48 . If EVAP canister does not need to be replaced, go to step  46 .
  45. Check EVAP canister purge valve control circuit for an open or short circuit. Repair as necessary. After repairs, go to step  48 . If circuit is okay, go to step  47 .
  46. Check for short or open in control circuit for EVAP canister vent valve or EVAP pressure switching solenoid. Repair as necessary. After repairs, go to step  48 . If circuit is okay, go to next step.
  47. Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
  48. After repairs, using scan tool, clear DTC information. Road test vehicle within freeze frame conditions that set DTC. Check for DTCs. If no DTCs are stored, repair is complete. If any DTCs are stored, diagnose affected DTC(s).
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