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Diagnosis & Repair (Using Toyota Scan Tester)

  1. Connect scan tester. See Figure. Turn ignition on. Read EGR gas temperature. If temperature is 50°F (10°C), go to step 5). If temperature is 37.6°F (3.1°C), there is an open EGR temperature sensor circuit. If temperature is not 50°F (10°C), go to next step.
  2. Disconnect EGR temperature sensor connector. Connect jumper wire between wiring harness connector terminals. If EGR temperature displayed is not about 316°F (158°C), go to next step. If temperature displayed is about 316°F (158°C), inspect sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest.
  3. Remove jumper wire. Turn ignition off. Access ECM under driver's seat. Connect jumper wire between terminals No. 12 (Brown/White wire) and No. 9 (Brown/Black wire) at ECM E6 connector. See Figure. Turn ignition on.
  4. If EGR temperature displayed is about 316°F (158°C), inspect and repair open in circuits between ECM and EGR temperature sensor. If temperature displayed is not about 316°F (158°C), replace ECM and retest.
  5. Inspect vacuum hoses. See appropriate illustration in VACUUM DIAGRAMS article. Repair as necessary. If all hoses are okay, inspect VSV. Using scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester. VSV is located under intake plenum cover.
  6. Start and run engine. With EGR system off, air from port "E" should exhaust from filter on end of valve. See Fig 1. With EGR system on, air from port "E" should exhaust from port "F". If VSV operates correctly, go to step 9). If VSV does not operate correctly, go to next step.
  7. Remove EGR VSV. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 37-44 ohms at 68°F (20°C). Check for continuity between each VSV terminal and body of valve. If continuity exists, replace VSV. If continuity does not exist, go to next step.
  8. Check VSV operation. Apply battery voltage to VSV terminals. Air from port "E" should exhaust from port "F". See Fig 1. Remove battery voltage from valve terminals. Air from port "E' should exhaust from filter on end of valve. Replace VSV as necessary. If VSV operates as specified, check for an open in wiring harness between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
  9. Inspect EGR vacuum modulator. See SYSTEM/COMPONENT TESTS article. Replace as necessary. If modulator is okay, inspect EGR valve. See SYSTEM/COMPONENT TESTS article. Replace as necessary. If components are okay, go to next step.
  10. Ensure all components are connected. Start and run engine. Using scan tester, select ACTIVE TEST mode (EGR system ON). Run engine at 3500 RPM for 3 minutes. Monitor EGR gas temperature. If temperature is 284°F (140°C) or more, replace ECM and retest. If temperature is less than 284°F (140°C), replace sensor.
Fig 1: Identifying EGR Vacuum Switching Valve (VSV)
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