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Diagnosis & Repair (Using Lexus Scan Tool)

  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 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 harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 1 (Yellow wire) and No. 22 (Brown wire) at ECM E9 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 system.
  4. Backprobing ECM harness connector, measure voltage between terminals No. 13 (Blue/Red wire) at ECM E8 connector and No. 22 (Brown wire) at ECM E9 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next to brake booster. Connect a vacuum pump to sensor. Voltage should be 3.0-3.7 volts with no vacuum applied and 0.5 volt with 1.2-19.7 in. Hg (8-135 kPa) applied. If voltage is as specified, 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. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. Turn ignition on. 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 8). If vacuum is not as specified, go to next step.
  7. Check EVAP VSV. See SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, 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 as necessary. If wiring is okay, replace ECM and retest system.
  8. Disconnect vapor pressure sensor VSV. Start and run engine. Using scan tool, select ACTIVE TEST mode. With VSV off, air should flow from port "G". See Figure. With VSV on, air should flow from port "F". If valve operates correctly, go to step 10). If valve does not operate correctly, go to next step.
  9. Check vapor pressure sensor VSV. See SYSTEM/COMPONENT TESTS article. Replace VSV as necessary. If VSV is okay, 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 system.
  10. Ensure vapor pressure sensor VSV is disconnected. Start and run engine. Select ACTIVE TEST mode on scan tool. Backprobing ECM harness connector, measure voltage between terminals No. 13 (Blue/Red wire) at ECM E8 connector and No. 22 (Brown wire) at ECM E9 connector. See Figure. With EVAP VSV activated, voltage should be less than 2 volts. If voltage is as specified, go to step 12). If voltage is not as specified, go to next step.
  11. Check vacuum hose between charcoal canister and vapor pressure sensor VSV and between vapor pressure sensor and vapor pressure sensor VSV. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  12. Remove fuel tank cap. Ensure vapor pressure sensor VSV is disconnected. Select ACTIVE TEST mode on scan tool. Start engine. Using scan tool, switch EVAP VSV on. Backprobing ECM harness connector, measure voltage between terminals No. 13 (Blue/Red wire) at ECM E8 connector and No. 22 (Brown wire) at ECM E9 connector 5 seconds after switching EVAP VSV from on to off. If voltage is 2.5 volts or less, replace ECM and retest system. If voltage is more than 2.5 volts, replace charcoal canister.
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