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Home >> Toyota >> 1996 >> 4Runner Base, RWD, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 2.7L >> Circuit Tests >> DTC P0402 - Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (Using OBD-II Scan Tester)
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Diagnosis & Repair (Using OBD-II Scan Tester)

  1. Disconnect EGR temperature sensor. Sensor is located on intake plenum. 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. Inspect circuits between EGR temperature sensor and ECM for short. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuits are okay, go to next step.
  3. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 33-39 ohms at 68°F (20°C). Check for continuity between each terminal and body of valve. If continuity exists, replace VSV. If continuity does not exist, go to next step.
  4. Check VSV operation. Apply battery voltage to VSV terminals. Air from port "E" should exhaust from port "F". See Figure. Remove battery voltage from valve terminals. Air from port "E" should not exhaust from port "F". Replace VSV as necessary. If VSV operates as specified, check EGR valve. See SYSTEM/COMPONENT TESTS article. If EGR valve is okay, go to next step.
  5. Check for an open circuit in wiring harness between engine compartment fuse block and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring harness is okay, replace ECM and retest.
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