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Diagnosis & Repair (OBD-II Scan Tester ONLY)

WARNING: This page is about a different car, the 1995 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
  1. Disconnect EGR gas temperature sensor. Sensor is located on manifold between EGR valve and intake plenum. Using ohmmeter, measure resistance between sensor terminals. If resistance is 600 k/ohms or less, go to next step. If resistance is NOT 600 k/ohms or less, inspect sensor. See the SYSTEM/COMPONENT TESTS article. Replace as needed.
  2. Turn ignition on. Using DVOM, measure voltage between sensor harness connector terminals. If voltage is 4.5-5.5 volts, go to step 4). If voltage is NOT 4.4-5.5 volts, go to next step.
  3. Access ECM behind right instrument panel speaker. Using DVOM, backprobe harness connector. Measure voltage between ECM terminals THG and E2. See Figure. If voltage is 4.5-5.5 volts, inspect circuits between EGR gas temperature sensor and ECM for open. See wiring diagram in the WIRING DIAGRAMS article. Repair as needed. If voltage is NOT 4.4-5.5 volts, replace ECM and retest.
  4. Inspect all EGR system vacuum hoses. Replace as needed. Check operation of EGR Vacuum Switching Valve (VSV). Access ECM behind right instrument panel speaker. Ensure ignition is off. Disconnect E6 harness connector. Turn ignition on. Using jumper wire, connect ECM terminal EGR to ground.
  5. VSV is located on intake plenum. With jumper wire connected, VSV is on. Air should NOT pass through valve. See Figure. Disconnect jumper wire. Air should pass through valve. If valve operates correctly, go to step 9).
  6. If valve does operate correctly, turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 30-34 ohms at 68°F (20°C). Measure resistance between each terminal and body of valve. Resistance should be infinite. Replace VSV as needed.
  7. Check VSV operation. Apply battery voltage to valve terminals. Air should NOT pass through valve. Remove battery voltage from valve terminals. Air should pass through valve. Replace as needed.
  8. If valve meets all specifications in steps 6) and 7), inspect circuits between EGR VSV and ECM. See wiring diagram in the WIRING DIAGRAMS article. Repair as needed.
  9. Inspect EGR vacuum modulator. See procedures in the SYSTEM/COMPONENT TESTS article. Replace as needed. Inspect EGR valve. See the SYSTEM/COMPONENT TESTS article. Replace as needed.
  10. Inspect EGR gas temperature sensor. Disconnect EGR gas temperature sensor harness connector. Start and run engine. Disconnect VSV connector for EGR. Run engine at 4000 RPM for 3 minutes. Measure resistance between sensor terminals after 3 minutes. Resistance should be 4.3 k/ohms or less.
  11. If resistance is NOT within specification, replace sensor. If resistance is within specification, replace ECM and retest.
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