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Diagnosis & Repair (Using Toyota Hand-Held Tester)

  1. Check EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor harness connectors for damaged pins, corrosion and loose wires. If problem exists, repair connectors as necessary. If problem does not exist, go to next step.
  2. Check all EVAP related vacuum hoses for cracks, looseness and correct routing. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  3. Access ECM behind bottom center of instrument panel, in front of console. Turn ignition on. Using DVOM, backprobe and measure voltage between terminals No. 1 (Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5. 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. Using DVOM, backprobe ECM connector and measure voltage between terminals No. 7 (Blue/Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5. Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and less than .5 volt with 1.18 in. Hg applied. If voltage is as specified, go to step  6. If voltage is not as specified, go to next step.
  5. Check for open or short in wiring between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  6. Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Turn ignition on. Using scan tool, select ACTIVE TEST mode. Disconnect vacuum hose from port "D" at charcoal canister (purge port). See Fig 1. 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  10. If vacuum is not as specified, go to next step.
  7. Check vacuum hose between intake manifold and EVAP VSV. Also check vacuum hose between EVAP VSV and charcoal canister. If problem exists, replace vacuum hoses as necessary. If problem does not exist, go to next step.
  8. Check EVAP VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace EVAP VSV. If problem does not exist, go to next step.
  9. Check for open or short in wiring between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  10. Disconnect vacuum hoses from vapor pressure sensor VSV. Turn ignition on. Apply air pressure to vapor pressure sensor VSV port "E". See Fig 2. Using scan tool, select ACTIVE TEST mode. When vapor pressure sensor VSV is activated by scan tool, air should flow from port "F". When vapor pressure sensor VSV is not activated, air should flow from port "G". If vapor pressure sensor VSV operates as specified, go to step  13. If vapor pressure sensor VSV does not operate as specified, go to next step.
  11. Check vapor pressure sensor VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace vapor pressure sensor VSV as necessary. If problem does not exist, go to next step.
  12. Check for open or short in wiring between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  13. Disconnect vapor pressure sensor VSV harness connector. Start and engine. Using scan tool, select ACTIVE TEST mode. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 7 (Blue/Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5. With EVAP VSV activated, voltage should be 2 volts or less. If voltage is as specified, go to step  15. If voltage is not as specified, go to next step.
  14. Check vacuum hose between charcoal canister and vapor pressure sensor VSV, and vacuum hose between vapor pressure sensor and vapor pressure sensor VSV. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  15. Remove fuel cap. Using scan tool, select ACTIVE TEST mode. Start engine. Using scan tool, switch EVAP VSV on. Using DVOM, backprobe ECM connector and measure voltage between terminals No. 7 (Blue/Yellow wire) and No. 9 (Brown wire) at ECM harness connector E5 5 seconds after switching EVAP VSV from on to off. Voltage should be 2.5 volts or less. If voltage is as specified, replace charcoal canister. If voltage is not as specified, go to next step.
  16. Check charcoal canister. Perform appropriate fuel EVAP system test. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, repair as necessary. If problem does not exist, replace ECM.
Fig 1: Identifying Ports At Charcoal Canister
G98J11881Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Identifying Vapor Pressure Sensor Vacuum Switching Valve (VSV) Ports
G96C10183Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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