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Home >> Toyota >> 1997 >> Land Cruiser >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Circuit Tests >> DTC P0402: Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tool)
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Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Disconnect EGR temperature sensor. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500 ohms or more, go to next step. If resistance is less than 2500 ohms, replace sensor.
  2. Check for short circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Access ECM behind right instrument panel speaker. Ensure ignition is off. Disconnect ECM E4 connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 22 (Blue/White wire) at ECM E4 connector.
  4. With jumper wire connected, Vacuum Switching Valve (VSV) is on. Apply air pressure to VSV port "G". Air from port "G" should not flow from port "E". See Figure. Disconnect jumper wire. Air from port "G" should flow from port "E". If VSV operates as specified, check EGR valve. See SYSTEM/COMPONENT TESTS article. If VSV does not operate as specified, go to next step.
  5. Remove EGR VSV. Air intake chamber may have to be removed to access VSV. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 30-34 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.
  6. Check for open circuit in wiring harness between VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, replace ECM and retest.
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