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Home >> Toyota >> 1998 >> Avalon XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes >> Self-Diagnostic Tests >> DTC P0441: Incorrect EVAP Purge Flow Or DTC P0446: EVAP Vent Control Fault >> Diagnosis & Repair (Using Toyota Scan Tool Except Calif. Emission Models Without Engine Immobilizer System &/Or Traction Control)
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Diagnosis & Repair (Using Toyota Scan Tool Except Calif. Emission Models Without Engine Immobilizer System &/Or Traction Control)

  1. Check EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor wiring harness connectors for damaged pins, corrosion and loose wires. Repair as necessary. If connectors are okay, go to next step. For component locations, see appropriate illustration in THEORY/OPERATION article.
  2. Check all EVAP related vacuum hoses for cracks, looseness and correct routing. Repair vacuum hoses as necessary. If vacuum hoses are okay, go to next step. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article.
  3. Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E7 connector. See Figure. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
  4. Backprobing ECM connector, measure voltage between terminal No. 13 (Pink wire) at ECM E6 connector and terminal No. 22 (Brown wire) at ECM E7 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is mounted on firewall, near brake booster. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied and 1.3-2.1 volts with .59 in. Hg (2 kPa) applied, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Connect scan tool to DLC No. 3. Turn ignition. Using scan tool, select ACTIVE TEST mode. Disconnect EVAP VSV vacuum hose from charcoal canister. Start engine. Connect a vacuum gauge to disconnected vacuum hose. When EVAP VSV is activated by scan tool, vacuum should be present. When EVAP VSV is not activated, no vacuum should be present. If vacuum is as specified, go to step 9). If vacuum is not as specified, go to next step.
  7. Check vacuum hose between intake manifold and EVAP VSV, and hose between EVAP VSV and charcoal canister. Replace vacuum hoses as necessary. If vacuum hoses are okay, check EVAP VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, go to next step.
  8. Check for an open or short in wiring harness between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace ECM.
  9. Turn ignition on. Using scan tool, select ACTIVE TEST mode. Locate vapor pressure sensor VSV on top of EVAP charcoal canister on left side of engine compartment. Apply air pressure to VSV port "E". See Figure. When vapor pressure sensor VSV is activated by scan tool, air should flow from port "F". When VSV is not activated, air should flow from port "G". If VSV operates as specified, go to step 12). If VSV does not operate as specified, go to next step.
  10. Check vapor pressure sensor VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, go to next step.
  11. Check for open or short circuit in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, replace ECM.
  12. Disconnect vapor pressure sensor VSV connector. VSV is mounted on top of EVAP charcoal canister on left side of engine compartment. Start and run engine. Using scan tool, select ACTIVE TEST mode. Backprobing ECM connector, measure voltage between terminal No. 13 (Pink wire) at ECM E6 connector and terminal No. 22 (Brown wire) at ECM E7 connector. See Figure. With EVAP VSV activated, voltage should be 2 volts or less. If voltage is as specified, go to step 14). If voltage is not as specified, go to next step.
  13. Check vacuum hose between charcoal canister and vapor pressure sensor VSV, and vacuum hose between vapor pressure sensor and vapor pressure sensor VSV. Repair vacuum hoses as necessary. If vacuum hoses are okay, go to next step.
  14. Remove fuel tank cap. Disconnect vapor pressure sensor VSV connector. Select ACTIVE TEST mode on scan tool. Start engine. Using scan tool, select ACTIVE TEST mode. Backprobing ECM connector, measure voltage between terminal No. 13 (Pink wire) at ECM E6 connector and terminal No. 22 (Brown wire) at ECM E7 connector 5 seconds after switching EVAP VSV from on to off. See Figure. If voltage is 2.5 volts or less, replace charcoal canister. If voltage is more than 2.5 volts, go to next step.
  15. Check charcoal canister. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM/COMPONENT TESTS article. Replace charcoal canister as necessary. If charcoal canister is okay, replace ECM.
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