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Diagnosis & Repair (Using OBD-II 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 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 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. If voltage is 3.0-3.7 volts without vacuum applied and .5 volt with 1.2-19.7 in. Hg (8-135 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 as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Disconnect EVAP VSV vacuum hoses. For VSV location, see VACUUM DIAGRAMS article. Apply air pressure to VSV port "E". See Fig 1. Air should not flow from port "F". Access ECM harness connectors behind glove box. Turn ignition on. Connect jumper wire between ground and terminal No. 2 (Light Green wire) at ECM E8 connector. See Figure. Air should flow from port "F". If VSV functions as specified, go to step 8). If VSV does not function as specified, go to next step.
  7. Check EVAP VSV operation. 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 vacuum hoses. VSV is mounted on top of EVAP charcoal canister. Apply air pressure to VSV port "E". See Figure. Air should flow from port "G". Access ECM harness connectors behind glove box. Turn ignition on. Connect jumper wire between ground and terminal No. 8 (White/Red wire) at ECM E8 connector. See Figure. Air should flow from port "F". If VSV does not function as specified, go to next step. If VSV functions as specified, check charcoal canister. See SYSTEM/COMPONENT TESTS article. Replace canister as necessary.
  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.
Fig 1: Identifying EVAP VSV Vacuum Ports
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