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Diagnosis & Repair (Using Toyota Scan Tool)

  1. Connect scan tool. See Figure. Turn ignition on. Read EGR gas temperature. If temperature is 50°F (10°C), go to step 6). If temperature is not 50°F (10°C), go to next step.
    NOTE: If EGR gas temperature is 37.6°F (3.1°C), an open exists in EGR temperature sensor circuit.
  2. Disconnect EGR temperature sensor connector. Sensor is mounted to EGR valve assembly. Connect a jumper wire between EGR temperature sensor connector terminals.
  3. If EGR temperature displayed is not 318.7°F (159.3°C), go to next step. If temperature displayed is 318.7°F (159.3°C), check sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest.
  4. Remove jumper wire. Turn ignition off. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION  under SELF-DIAGNOSTIC SYSTEM. Connect a jumper wire between terminals No. 46 and 65 at Check Harness "B" connector. See Figure. Turn ignition on.
  5. If EGR temperature displayed is 318.7°F (159.3°C), locate and repair open circuit in wiring harness between ECM and EGR temperature sensor. If temperature displayed is not 318.7°F (159.3°C), replace ECM and retest.
  6. Check vacuum hoses. See appropriate illustration in VACUUM DIAGRAMS - NON-TURBO article. Replace vacuum hoses as necessary. If all hoses are okay, check EGR VSV. Using scan tool, select ACTIVE TEST mode. Check operation of EGR VSV when activated by scan tool. EGR VSV is located near intake manifold at left front of engine.
  7. Apply air pressure to EGR VSV port "E". With EGR system off, air from port "E" should not flow from port "F". See Fig 1. With EGR system on, air from port "E" should flow from port "F". If valve operates as specified, go to step 11). If valve does not operate as specified, go to next step.
  8. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 39-45 ohms at 68°F (20°C). Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is not as specified, replace EGR VSV. If resistance is as specified, go to next step.
  9. Check EGR VSV operation. Apply battery voltage to EGR VSV terminals. Apply air pressure to EGR VSV port "E". Air from port "E" should flow from port "F". See Fig 1. Remove battery voltage from valve terminals. Air from port "E" should not flow from port "F". Replace EGR VSV as necessary.
  10. If VSV meets all specifications in steps 8) and 9), check circuits between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS - NON-TURBO article. Repair wiring as necessary.
  11. Check EGR vacuum modulator. See SYSTEM/COMPONENT TESTS - NON-TURBO article. Replace as necessary. If EGR vacuum modulator is okay, check EGR valve. See SYSTEM/COMPONENT TESTS - NON-TURBO article. Replace EGR valve as necessary. If components are okay, go to next step.
  12. Ensure all components are connected. Start and run engine. Using scan tool, select ACTIVE TEST mode (EGR system ON). Run engine at 4000 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 Vacuum Switch Valve (Typical)
G96B10182Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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