Diagnosis & Repair (Using Lexus Scan Tester)

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.
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.
Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E13 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.
Backprobing ECM harness connector, measure voltage between terminals No. 18 (Pink/Green wire) at ECM E11 connector and No. 22 (Brown wire) at ECM E13 connector. Disconnect vacuum hose from vapor pressure sensor. Voltage reading should be as follows:
- 3.0-3.6 volts with no vacuum applied.
- 4.2-4.8 volts with .22 psi (1.5 kPa) applied.
- 1.3-2.1 volts with .59 in. Hg (2.0 kPa) applied.
If voltage is as specified, go to step 6). If voltage is not as specified, go to next step.
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.
Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. See Figure. Turn ignition and scan tester on. Using scan tester, 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 tester, vacuum should be present. When EVAP VSV is not activated, no vacuum should be present. If vacuum is as specified, go to step 9). If vacuum is not as specified, go to next step.
Check EVAP VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Replace VSV as necessary. If VSV is okay, go to next step.
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.
Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. See Figure. Turn ignition and scan tester on. Disconnect vapor pressure sensor VSV. Start and run engine. Select ACTIVE TEST mode on scan tester. Backprobing ECM harness connector, measure voltage between terminals No. 18 (Pink/Green wire) at ECM E11 connector and No. 22 (Brown wire) at ECM E13 connector. See Figure. With EVAP VSV activated, voltage should be less than 2 volts. If voltage is as specified, go to step 11). If voltage is not as specified, go to next step.
Check vapor pressure sensor VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Replace VSV as necessary. If VSV is okay, go to next step.
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, go to next step.
Remove fuel tank cap. Disconnect vapor pressure sensor VSV. Select ACTIVE TEST mode on scan tester. Start engine. Using scan tester, switch EVAP VSV on. Backprobing ECM harness connector, measure voltage between terminals No. 18 (Pink/Green wire) at ECM E11 connector and No. 22 (Brown wire) at ECM E13 connector 5 seconds after switching EVAP VSV from on to off. If voltage is 2.5 volts or less, replace ECM and retest. If voltage is more than 2.5 volts, replace charcoal canister.