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Home >> Toyota >> 1996 >> T100 Base, 2D Pickup, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System Tests W/Codes - 3.4L >> Circuit Tests >> DTC P0402 - Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected (2WD Models) >> 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 at right rear of engine. 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 a short circuit in wiring harness between EGR temperature sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
  3. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM E5 connector (A/T models) or E7 connector (M/T models). Turn ignition on. On A/T models, connect a jumper wire between ground and terminal No. 8 (Red/White wire) at ECM E5 connector. On M/T models, connect a jumper wire between ground and terminal No. 18 (Red/White wire) at ECM E7 connector.
  4. With jumper wire connected, Vacuum Switching Valve (VSV) is on. Air from port "E" should exhaust through filter on end of valve. See Figure. Disconnect jumper wire. Air from port "E" should exhaust from port "G". If valve operates correctly, check EGR valve. See SYSTEM/COMPONENT TESTS article. If valve does not operate correctly, go to next step.
  5. Turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 33-39 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 VSV. If resistance is as specified, go to next step.
  6. Check VSV operation. Apply battery voltage to VSV terminals. Air from port "E" should exhaust from small filter on end of valve. Remove battery voltage from valve terminals. Air from port "E " should exhaust from port "G". Replace VSV as necessary. If VSV operates as specified, go to next step.
  7. Check for short circuit in wiring harness between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.
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