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Home >> Toyota >> 2000 >> RAV4 Base, AWD, Standard >> Repair and Diagnosis (Single Page) >> External Pages >> Different car >> Section 17 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P0441: Incorrect EVAP Purge Flow, Or DTC P0446: EVAP Vent Control Circuit >> Diagnosis & Repair
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Diagnosis & Repair

WARNING: This page is about a different car, the 2000 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check for cracks, deformations in fuel tank, charcoal canister and fuel tank filler pipe. Check for disconnected hoses and tubes around fuel tank and charcoal canister. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel cap. If fuel cap is not an OEM cap, replace cap with an OEM cap. If fuel cap is an OEM cap, go to next step.
  3. Check if fuel cap is properly installed. If problem exists, install fuel cap properly. If fuel cap is properly installed, go to next step.
  4. Check for damaged fuel cap and gasket. If problem exists, replace fuel cap with OEM cap. If problem does not exist, go to next step.
  5. Remove fuel cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between charcoal canister and pressure switching valve VSV. Check hoses for correct installation, looseness and damage. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check all EVAP system electrical component connections. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check vacuum hoses between charcoal canister and fuel tank, and between fuel filler neck and fuel tank. If problem exists, repair as necessary. If problem does not exist, go to next step.
  10. Access ECM below stereo, behind instrument panel, just in front of center console. Turn ignition on. Using DVOM, backprobe ECM harness connector. On models with 4A/T transmission, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E8. See Figure. On models without 4A/T transmission, measure voltage between terminals No. 1 (Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5. See Figure. On all models, voltage should be 4.5-5.5 volts. If voltage is not as specified, replace ECM. If voltage is as specified, go to next step.
  11. Using DVOM, backprobe ECM harness connector. On models with 4A/T transmission, measure voltage between terminals No. 9 (Blue wire) and No. 18 (Brown wire) at ECM harness connector E8. On models without 4A/T transmission, measure voltage between terminal No. 17 (Blue wire) at ECM harness connector E4 and terminal No. 9 (Brown wire) at ECM harness connector E5. On all models, disconnect vacuum hose from vapor pressure sensor. See Figure. Vapor pressure sensor is mounted on charcoal canister. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and .5 volt or less with 1.8 in. Hg applied. If voltage is as specified, go to step  13. If voltage is not as specified, go to next step.
  12. Check for an open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  13. Disconnect EVAP VSV vacuum hoses. Turn ignition on. Access ECM below stereo, behind instrument panel, just in front of center console. On models with 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 4 (Blue/Black wire) at ECM harness connector E8. See Figure. On models without 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 7 (Blue/Black wire) at ECM harness connector E4. See Figure. On all models, with jumper wire connected air applied to EVAP VSV port "E" should flow from port "F". See Fig 1. Remove jumper wire. With jumper wire removed, air applied to EVAP VSV port "E" should not flow from port "F". If EVAP VSV functions as specified, go to step  16. If EVAP VSV does not function as specified, go to next step.
  14. Check EVAP VSV operation. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If EVAP VSV is okay, go to next step. If EVAP VSV is not okay, replace EVAP VSV. Also clean vacuum hose between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister, then check charcoal canister. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article.
  15. Check for an open or short in wiring between engine room junction box and EVAP VSV, and between EVAP VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  16. Disconnect canister closed valve VSV vacuum hoses. Turn ignition on. Access ECM below stereo, behind instrument panel, just in front of center console. On models with 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 17 (Blue/Black wire) at ECM harness connector E7. On models without 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 5 (Blue/Black wire) at ECM harness connector E4. On all models, with jumper wire connected air applied to canister closed valve VSV port "B" should not flow from port "A". See Fig 2. Remove jumper wire. With jumper wire removed, air applied to canister closed valve VSV port "B" should flow from port "A". If canister closed valve VSV does not function as specified, go to next step. If canister closed valve VSV functions as specified, go to step  19.
  17. Check canister closed valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If canister closed valve VSV is okay, go to next step. If canister closed valve VSV is defective, replace canister closed valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and canister closed valve VSV.
  18. Check for an open or short in wiring between engine room junction box and canister closed valve VSV, and between canister closed valve VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  19. Disconnect pressure switching valve VSV vacuum hoses. Turn ignition on. Access ECM below stereo, behind instrument panel, just in front of center console. On models with 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 22 (Red wire) at ECM harness connector E7. On models without 4A/T transmission, connect a jumper wire by backprobing between ground and terminal No. 4 (Red wire) at ECM harness connector E4. On all models, with jumper wire connected air applied to pressure switching valve VSV port "E" should flow from port "F". See Fig 3. Remove jumper wire. With jumper wire removed, air applied to pressure switching valve VSV port "E" should not flow from port "F". If pressure switching valve VSV functions as specified, go to step  22. If pressure switching valve VSV does not function as specified, go to next step.
  20. Check pressure switching valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If pressure switching valve VSV is defective, replace pressure switching valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and pressure switching valve VSV, and between pressure switching valve VSV and fuel tank. If pressure switching valve VSV is okay, go to next step.
  21. Check for an open or short in wiring between engine room junction box and pressure switching valve VSV, and between pressure switching valve VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  22. Charcoal canister or fuel tank overfill check valve maybe defective. Check fuel evaporation system. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Repair as necessary. If no problem is indicated, replace ECM.
Fig 1: Identifying EVAP VSV Vacuum Ports
G96D09634Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Identifying Canister Closed Valve VSV Vacuum Ports
G99D52749Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Identifying Pressure Switching Valve VSV Vacuum Ports
G00011096Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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