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Home >> Toyota >> 2000 >> 4Runner Base, RWD, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Self-Diagnostics - 4-Cylinder >> Diagnostic 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 harness connector. Measure resistance between EGR temperature sensor terminals (component side). If resistance is 2500 ohms or more, go to next step. If resistance is less than 2500 ohms, replace EGR temperature sensor.
  2. Check for short in wiring between EGR temperature sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  3. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM harness connector E6. See Figure or Figure . Turn ignition on. On models with California emissions, connect a jumper wire between ground and terminal No. 5 (Pink/Black wire) at ECM harness connector E6. On models without California emissions, connect a jumper wire between ground and terminal No. 15 (Pink/Black wire) at ECM harness connector E6. On all models with jumper wire connected, air applied to port "E" of EGR VSV should flow from port "F". See Figure. Disconnect jumper wire. Air applied to port "E" of EGR VSV should not flow from port "F". If EGR VSV operates as specified, check EGR valve. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If EGR VSV does not operate as specified, go to next step.
  4. Turn ignition off. Disconnect EGR VSV harness connector. Measure resistance between EGR VSV terminals. Resistance should be 33-39 ohms at 68°F (20°C). Measure resistance between each terminal and body of EGR VSV. Resistance should be infinite. If resistances are not as specified, replace EGR VSV. If resistances are as specified, go to next step.
  5. Apply battery voltage to EGR VSV terminals. Apply air pressure to EGR VSV port "E". Air should flow from port "F". See Figure. Remove battery voltage from EGR VSV terminals. Air should not flow from port "F". If EGR VSV operates as specified, go to next step. If EGR VSV does not operate as specified, replace EGR VSV.
  6. Check for open in wiring between engine compartment fuse block and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
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