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Home >> Toyota >> 1996 >> 4Runner Base, 4WD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 2.7L >> Circuit Tests >> DTC P0441 - Incorrect EVAP Purge Flow DTC P0446 - Vent Control Malfunction >> Diagnosis & Repair (Using OBD-II Scan Tester)
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Diagnosis & Repair (Using OBD-II Scan Tester)

  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 - 2.7L article.
  2. Check all EVAP related vacuum hoses for cracks, looseness and correct routing. Repair 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 (Green/Yellow wire) and No. 9 (Brown/Black 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 and retest.
  4. Backprobe ECM connector. On A/T models, measure voltage between terminals No. 18 (Light Green/Black wire) at ECM E6 connector and No. 9 (Brown/Black wire) at ECM E7 connector. On M/T models, measure voltage between terminals No. 10 (Light Green/Black wire) and No. 9 (Brown/Black wire) at ECM E7 connector. On all models, disconnect vacuum hose from vapor pressure sensor. Sensor is located in left rear side of engine compartment. Connect a vacuum pump to sensor. If voltage is 3.0-3.6 volts without vacuum applied and 1.3-2.1 volts with .59 in. Hg (2 kPa) vacuum 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 as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Access ECM behind glove box. Turn ignition on. On A/T models, connect a jumper wire between ground and terminal No. 1 (Black/White wire) at ECM E8 connector. On M/T models, connect a jumper wire between ground and terminal No. 23 (Black/White wire) at ECM E6 connector. On all models, with jumper wire connected EVAP Vacuum Switching Valve (VSV) is on. Air from port "E" should exhaust from port "F". See Figure. Disconnect jumper wire. Air from port "E" should not exhaust from port "F". If VSV operates as specified, go to step 9). If VSV does not operated as specified, go to next step.
  7. Remove EVAP VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 30-34 ohms at 68°F (20°C). Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is not as specified, replace VSV. If resistance is as specified, go to next step.
  8. Check VSV operation. Apply battery voltage to VSV terminals. Air from port "E" should exhaust from port "F". See Figure. Remove battery voltage from valve terminals. Air from port "E" should not exhaust from port "F". Replace VSV as necessary. If VSV operates as specified, go to next step.
  9. Check for an open or short circuit in wiring harness between EVAP VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  10. Access ECM behind glove box. Turn ignition on. On A/T models, connect a jumper wire between ground and terminal No. 2 (Black/White wire) at ECM E8 connector. On M/T models, connect a jumper wire between ground and terminal No. 21 (Black/White wire) at ECM E6 connector. On all models, with jumper wire connected vapor pressure sensor Vacuum Switching Valve (VSV) is on. Air from port "E" should exhaust from port "F". See Figure. Disconnect jumper wire. Air from port "E" should exhaust from port "G". If VSV operates as specified, check charcoal canister. See SYSTEM/COMPONENT TESTS article. If VSV does not operated as specified, go to next step.
  11. Disconnect vapor pressure sensor VSV vacuum hoses. VSV is mounted on top of EVAP charcoal canister. Using ohmmeter, measure resistance between VSV terminals. If resistance is 37-44 ohms at 68°F (20°C), go to next step. If resistance is not 37-44 ohms, replace VSV.
  12. Check for continuity between each VSV terminal and VSV body. If continuity exists, replace VSV. If continuity does not exist, apply air pressure to VSV port "E". See Figure. Air from port "E" should exhaust from port "G". Apply battery voltage to VSV terminals. Air from port "E" should exhaust from port "F". If VSV operates as specified, go to next step. If VSV does not operate as specified, replace VSV.
  13. Check for an open or short in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.
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