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Home >> Toyota >> 1995 >> Tercel Base, Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Testing >> Code P0402 - Excessive Exhaust Gas RECIRCULATION (EGR) Flow Detected >> Diagnosis & Repair (OBD-II Scan Tester ONLY)
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Diagnosis & Repair (OBD-II Scan Tester ONLY)

  1. Inspect all EGR system vacuum hoses. Replace as needed. Inspect EGR valve. See the SYSTEM/COMPONENT TESTS article. Replace as needed.
  2. Check operation of EGR Vacuum Switching Valve (VSV). Access ECM. ECM is located behind glove box. Ensure ignition is off. Disconnect E6 harness connector. Turn ignition on. Using jumper wire, connect ECM terminal EGR to ground.
  3. VSV is located on cylinder head, below EGR vacuum modulator. With jumper wire connected, VSV is on. Air should flow through valve. Disconnect jumper wire. Air should NOT flow through valve. If valve operates correctly, go to step 7).
  4. If valve does operate correctly, 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. Replace VSV as needed.
  5. Check VSV operation. Apply battery voltage to valve terminals. Air should flow through valve. Remove battery voltage from valve terminals. Air should NOT flow through valve. Replace as needed.
  6. If valve meets all specifications in steps 4) and 5), inspect circuits between EGR VSV and ECM. See wiring diagram in the WIRING DIAGRAMS article. Repair as needed.
  7. Inspect EGR vacuum modulator. See procedures in the SYSTEM/COMPONENT TESTS article. Replace as needed. Inspect MAP sensor. See the SYSTEM/COMPONENT TESTS article. Replace as needed. If sensor is okay, replace ECM and retest.
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