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Home >> Toyota >> 2008 >> Prius Base >> Repair and Diagnosis >> Engine Performance >> Engine Control System >> SFI System >> DTC P0446 Evaporative Emission Control System Vent Control Circuit >> Inspection Procedure
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Inspection Procedure

  1. CONFIRM DTC 
    1. Turn the power switch OFF and wait for 10 seconds.
    2. Turn the power switch ON (IG).
    3. Turn the power switch OFF and wait for 10 seconds.
    4. Connect Techstream to the DLC3.
    5. Turn the power switch ON (IG).
    6. Enter the following menus: Powertrain / Engine and ECT / Trouble Code.
    7. Check if DTC P0446 is output.

    NO:  Go to step  5

    YES: Go to next step 

  2. PERFORM EVAPORATIVE SYSTEM CHECK 
    1. Note the freeze frame data and DTCs.
    2. Clear the DTCs.
    3. Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
    4. After the system check is finished, check for pending DTCs.

      OK: 

      No DTC is present. 

    NG:  Go to step  6

    OK: Go to next step 

  3. CHECK OPERATION OF PURGE FLOW SWITCHING VALVE 
    1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Tank Bypass.
    2. Touch the purge flow switching valve (TANK BYPASS VSV) to feel the operating vibration.

      OK: 

      The purge flow switching valve is operated by the Active Test. 

    NG:  Go to step  18

    OK: Go to next step 

  4. CHECK PURGE FLOW SWITCHING VALVE 
    1. Turn the power switch OFF.
    2. Remove the purge flow switching valve.
    3. Reconnect the purge flow switching valve connector.
    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Tank Bypass.
    5. Check the airflow for the purge flow switching valve.

      OK: 

      The purge flow switching valve operates normally. 

    NG:  Go to step  19

    Fig 1: Checking Purge Flow Switching Valve
    G05188749Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK:  Go to step  33

  5. PERFORM EVAPORATIVE SYSTEM CHECK 
    1. Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
    2. After the system check is finished, check for pending DTCs.

      OK: 

      DTCs are present. 

    NG: CHECK FOR INTERMITTENT PROBLEMS 

    OK: Go to next step 

  6. CHECK DTC 
    1. Check the DTCs that were present in the EVAP system check.

      OK: 

      P043E, P043F, P2401, P2402 and P2419 are present. 

    NG:  Go to step  10

    OK: Go to next step 

  7. CHECK VENT VALVE CLOSE STUCK 
    1. Allow the engine to idle.
    2. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Evap Control.
    3. Turn the EVAP VSV ON (purge VSV open) and check the VAPOR PRESS (EVAP pressure) for 10 seconds.

      OK: 

      EVAP pressure is higher than 755 mmHg. 

    NG:  Go to step  20

    OK: Go to next step 

  8. CHECK LEAK DETECTION PUMP OPERATION 
    1. Turn the power switch OFF.
    2. Turn the power switch ON (IG).
    3. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Vacuum Pump.
    4. Touch the pump module to feel the operating vibration.

      OK: 

      The leak detection pump is operated by the Active Test. 

    NG:  Go to step  21

    OK: Go to next step 

  9. CHECK TRAP CANISTER 
    1. Disconnect the vent hose from the pump module.
    2. Check that no moisture is in the pump module or the vent hose.

      OK: 

      No moisture. 

    OK:  Go to step  22

    NG:  Go to step  23

    Fig 2: Locating Pump Module
    G05188750Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  10. CHECK DTC 
    1. Check the DTCs that were present in the EVAP system check.

      OK: 

      P0441, P0455 and/or P0456 are present. 

    NG:  Go to step  16

    NG: Go to next step 

  11. CHECK INSTALLATION CONDITIONS OF FUEL CAP 
    1. Remove the fuel cap.
    2. Reinstall the fuel cap.
    3. Clear the DTCs.
    4. Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
    5. After the system check is finished, check for pending DTCs.

      HINT:

      If no DTC is present, this indicates that the fuel cap is loosened.

      OK: 

      No DTC is present. 

    OK: REPAIR COMPLETED 

    NG: Go to next step 

  12. LOCATE LEAK POINT 
    1. Disconnect the vent hose (fresh air line) as shown in the illustration.
      Fig 3: Identifying Canister Filter, Canister And Vent Hose
      G05188751Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect the pressure gauge and air pump as shown in the illustration.
    3. Pressurize the EVAP system until the pressure reaches 24 to 28 mmHg.
    4. Locate the leak point.

      HINT:

      If the EVAP system has leakage, a whistling sound may be heard.

      OK: 

      The leak point is found. 

    OK:  Go to step  24

    NG: Go to next step 

  13. CHECK FUEL CAP 

    Check that the fuel cap meets OEM specifications.

    HINT:

    If an EVAP tester is available, perform the fuel cap test according to the tester's instructions.

    OK: 

    Fuel cap meets OEM specifications. 

    NG:  Go to step  25

    OK: Go to next step 

  14. CHECK OPERATION FOR PURGE VSV 
    1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Evap Control.
    2. Touch the purge VSV to feel the operating vibration.

      OK: 

      The purge VSV (EVAP VSV) is operated by the Active Test. 

    NG:  Go to step  26

    OK: Go to next step 

  15. CHECK INTAKE MANIFOLD PRESSURE 
    1. Disconnect the purge VSV hose that is connected to the throttle body.
    2. Allow the engine to idle.
    3. Check that the hose has suction using your finger.

      OK: 

      The hose has suction. 

    NG:  Go to step  27

    OK:  Go to step  28

    Fig 4: Locating Purge VSV Hose And Hose
    G05188752Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  16. CHECK DTC 
    1. Check the DTCs that were present in the EVAP system check.

      OK: 

      P0451 is not present. 

    NG:  Go to step  9

    OK: Go to next step 

  17. CHECK OPERATION FOR VENT VALVE 
    1. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Vent Valve.
    2. Touch the pump module to feel the operating vibration.

      OK: 

      The vent valve is operated by the Active Test. 

    OK:  Go to step  9

    NG:  Go to step  29

  18. CHECK HARNESS AND CONNECTOR (PURGE FLOW SWITCHING VALVE - ECM AND EFI M RELAY) 
    1. Check the harness and the connectors between the purge flow switching valve and the ECM.
      1. Disconnect the V8 purge flow switching valve connector.
        Fig 5: Identifying V8 Purge Flow Switching Valve Connector
        G05674144Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      2. Disconnect the E7 ECM connector.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V8-1 (Purge flow switching valve) - E7-18 (TBP) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V8-1 (Purge flow switching valve) or E7-18 (TBP) - Body ground 10 kΩ or higher
        Fig 6: Identifying E7 ECM Connector Terminal
        G05188754Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Reconnect the purge flow switching valve connector.
      5. Reconnect the ECM connector.
    2. Check the harness and the connectors between the purge flow switching valve and the EFI M relay.
      1. Disconnect the V8 purge flow switching valve connector.
      2. Remove the integration relay from the engine room relay block.
      3. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V8-2 (Purge flow switching valve) - 3I-8 (EFI M relay) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V8-2 (Purge flow switching valve) or 3I-8 (EFI M relay) - Body ground 10 kΩ or higher
        Fig 7: Identifying Engine Room Relay Block
        G05188625Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Reconnect the purge flow switching valve connector.
      5. Reinstall the integration relay.

    NG:  Go to step  30

    OK:  Go to step  31

  19. REPLACE PURGE FLOW SWITCHING VALVE 

    Replace the purge flow switching valve.

    NEXT:  Go to step  34

  20. CHECK FOR VENT HOSE CLOG 
    1. Turn the power switch OFF.
    2. Disconnect the vent hose (fresh air line) as shown in the illustration.
    3. Allow the engine to idle.
    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for Evap Control.
    5. Turn the purge VSV (EVAP VSV) ON and check the EVAP pressure (VAPOR PRESS) for 10 seconds.

      OK: 

      EVAP pressure is higher than 755 mmHg. 

    NG:  Go to step  22

    Fig 8: Locating Pump Module
    G05188750Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK:  Go to step  32

  21. CHECK HARNESS AND CONNECTOR (LEAK DETECTION PUMP - ECM) 
    1. Disconnect the V7 canister pump module connector.
      Fig 9: Identifying V7 Canister Pump Module Connector
      G05674103Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E7 ECM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      V7-1 (MTRB) - E7-13 (MPMP) Below 1 Ω
      V7-6 (MGND) - Body ground Below 1 Ω

      Standard resistance (Check for short) 

      TESTER CONNECTION SPECIFIED CONDITION

      Tester Connection Specified Condition
      V7-1 (MTRB) or E7-13 (MPMP) - Body ground 10 kΩ or higher
      Fig 10: Identifying E7 ECM Connector Terminal
      G05188758Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Reconnect the canister pump module connector.
    5. Reconnect the ECM connector.

    NG:  Go to step  30

    OK:  Go to step  31

  22. REPLACE TRAP CANISTER WITH PUMP MODULE 

    Replace the trap canister with pump module (see REMOVAL ).

    NEXT:  Go to step  34

  23. CHECK FOR VENT HOSE DAMAGE 

    Check for hose damage as shown in the illustration. If necessary, replace the vent hose.

    Fig 11: Identifying Vent Hose Damage Area
    G05188759Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NEXT:  Go to step  22

  24. REPAIR OR REPLACE LEAK POINT 

    NEXT:  Go to step  34

  25. REPLACE FUEL CAP 

    NEXT:  Go to step  34

  26. CHECK HARNESS AND CONNECTOR (PURGE VSV - ECM) 
    1. Disconnect the V1 purge VSV connector.
      Fig 12: Identifying V1 Purge VSV Connector
      G05188760Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E5 ECM connector.
    3. Check the harness and the connectors between the ECM and the purge VSV connectors.
      1. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V1-1 - E5-14 (EVP1) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V1-1 or E5-14 (EVP1) - Body ground 10 kΩ or higher
        Fig 13: Identifying E5 ECM Connector Terminal
        G05188761Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Remove the integration relay from the engine room relay block.
    5. Check the harness and connectors between the purge VSV connector and the EFI M relay.
      1. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V1-2 - 3I-8 (EFI M relay) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V1-2 or 3I-8 (EFI M relay) - Body ground 10 kΩ or higher
        Fig 14: Identifying Engine Room Relay Block
        G05188625Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    6. Reconnect the purge VSV connector.
    7. Reconnect the ECM connector.
    8. Reinstall the integration relay.

    NG:  Go to step  30

    OK:  Go to step  31

  27. REPLACE HOSE (PURGE VSV - THROTTLE BODY) 

    NEXT:  Go to step  34

  28. REPLACE PURGE VSV 

    Replace the purge VSV.

    NEXT:  Go to step  34

  29. CHECK HARNESS AND CONNECTOR (VENT VALVE - ECM) 
    1. Disconnect the V7 canister pump module connector.
      Fig 15: Identifying V7 Canister Pump Module Connector
      G05674109Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the E7 ECM connector.
    3. Check the harness and the connectors between the ECM and the canister connectors.
      1. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V7-8 (VGND) - E7-26 (VPMP) Below 1 Ω

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V7-8 (VGND) or E7-26 (VPMP) - Body ground 10 kΩ or higher
        Fig 16: Identifying E7 ECM Connector Terminal
        G05188764Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Remove the integration relay from the engine room relay block.
    5. Check the harness and connectors between the canister connector and the EFI M relay.
      1. Measure the resistance according to the value(s) in the table below.

        Standard resistance (Check for open) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V7-9 (VLVB) - 3I-8 (EFI M relay) Below 1 Ω
        Fig 17: Identifying Engine Room Relay Block
        G05188625Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard resistance (Check for short) 

        TESTER CONNECTION SPECIFIED CONDITION

        Tester Connection Specified Condition
        V7-9 (VLVB) or 3I-8 (EFI M relay) - Body ground 10 kΩ or higher
    6. Reconnect the canister pump module connector.
    7. Reconnect the ECM connector.
    8. Reinstall the integration relay.

    NG: Go to step 30 

    OK:  Go to step  31

  30. REPAIR OR REPLACE HARNESS OR CONNECTOR 

    NEXT:  Go to step  34

  31. REPLACE ECM 

    Replace the ECM (see REMOVAL  ).

    NEXT:  Go to step  34

  32. CHECK AND REPLACE VENT HOSE OR CANISTER FILTER 

    NEXT:  Go to step  34

  33. REPLACE HOSE (PURGE FLOW SWITCHING VALVE AND FUEL TANK) 
  34. PERFORM EVAPORATIVE SYSTEM CHECK 
    1. Turn the power switch ON (IG).
    2. Enter the following menus: Powertrain / Engine and ECT / Utility / Evaporative System Check / Automatic Mode.
    3. After the system check is finished, check for pending DTCs.

      OK: 

      No DTC is present. 

    NG:  Go to step  6

    OK: Go to next step 

  35. PERFORM EVAP MONITOR DRIVE PATTERN 
    1. Check that the following conditions are met:
      • Fuel level is 1/8 to 7/8.
      • Engine coolant temperature (ECT) is 4.4 to 35°C (40 to 95°F).
      • Intake air temperature (IAT) is 4.4 to 35°C (40 to 95°F).
      • Difference between ECT and IAT is less than 7°C (13°F).
    2. Enter the check mode. Enter the following menus: Powertrain / Engine and ECT / Utility / Check Mode.
    3. Allow the engine to idle until the ECT is 75°C (167°F).
    4. Drive the vehicle at 50 km/h (30 mph) or faster and maintain that speed for 60 seconds or more.
    5. Stop the vehicle. Do not turn the power switch OFF.
    6. Check that the EVAP monitor status is complete. Enter the following menus: Powertrain / Engine and ECT / Monitor / Evaporative System.
    7. If the EVAP monitor is incomplete, drive the vehicle at 50 km/h (30 mph) or faster and maintain that speed for 120 seconds or more. After that, recheck the EVAP monitor status.
    8. Check for pending DTCs.

      OK: 

      No DTC is present. 

    NG:  Go to step  2

    OK: REPAIR COMPLETED 

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