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HOMESERVICE MANUALSTOYOTA2000TACOMA BASE, 2D PICKUP, 2.4 L, STANDARDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 4-CYLINDERDIAGNOSTIC TESTSDTC P0401: INSUFFICIENT EXHAUST GAS RECIRCULATION (EGR) FLOW DETECTEDDIAGNOSIS & REPAIR (USING TOYOTA HAND-HELD TESTER)
2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, Standard

Diagnosis & Repair (Using Toyota Hand-Held Tester)

2000 Toyota Tacoma Base, 2D Pickup, 2.4 L, StandardSECTION Diagnosis & Repair (Using Toyota Hand-Held Tester)
NOTE: If EGR gas temperature is 37.6°F (3.1°C), an open exists in EGR temperature sensor circuit.
  1. Connect Toyota hand-held tester to Data Link Connector. See Figure. Turn ignition on. Using hand-held tester, read EGR gas temperature. If EGR gas temperature displayed on hand-held tester is 50°F (10°C) or more, go to step  4. If EGR gas temperature displayed on hand-held tester is less than 50°F (10°C), go to next step.
  2. Disconnect EGR temperature sensor harness connector. Connect a jumper wire between EGR temperature sensor harness connector terminals. If EGR gas temperature displayed on hand-held tester is not 318.7°F (159.3°C), go to next step. If EGR gas temperature displayed on hand-held tester is 318.7°F (159.3°C), check EGR gas temperature sensor connectors and terminals. Repair as necessary. If connectors are okay, replace EGR temperature sensor.
  3. Remove jumper wire. Turn ignition off. Access ECM behind glove box. On models with California emissions, connect a jumper wire by backprobing between terminals No. 18 (Brown/Black wire) and No. 19 (Pink wire) at ECM harness connector E7. See Figure. On models without California emissions, connect a jumper wire by backprobing between terminals No. 9 (Brown/Black wire) and No. 11 (Pink wire) at ECM harness connector E7. See Figure. On all models, turn ignition on. If EGR gas temperature displayed on hand-held tester is 318.7°F (159.3°C), repair open in wiring between ECM and EGR temperature sensor. If EGR gas temperature displayed on hand-held tester is not 318.7°F (159.3°C), replace ECM.
  4. Check vacuum hoses. See appropriate illustration in VACUUM DIAGRAMS article. If problem exists, replace vacuum hoses as necessary. If problem does not exist, go to next step.
  5. Disconnect vacuum hoses from EGR VSV. Using hand-held tester, select ACTIVE TEST mode. Check operation of EGR VSV when activated by hand-held tester. Apply air pressure to EGR VSV port "E". With EGR system off, air should flow from port "F". See Fig 1. With EGR system on, air should not flow from port "F". If EGR VSV operates as specified, go to step  8. If EGR VSV does not operate as specified, go to next step.
  6. 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.
  7. Apply battery voltage between EGR VSV terminals. Apply air pressure to EGR VSV port "E". Air should flow from port "F". See Fig 1. Remove battery voltage from EGR VSV terminals. Air should not flow from port "F". If EGR VSV operates as specified, repair open in wiring between EGR VSV and ECM. If EGR VSV does not operate as specified, replace EGR VSV.
  8. Check EGR system components. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check EGR vacuum modulator. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace EGR vacuum modulator. If problem does not exist, go to next step.
  10. Check EGR valve. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If problem exists, replace EGR valve. If problem does not exist, go to next step.
  11. Ensure all components are connected. Start and run engine. Using hand-held tester, select ACTIVE TEST mode (EGR system ON). Run engine at 4000 RPM for 3 minutes. Monitor EGR gas temperature. If EGR gas temperature displayed on hand-held tester is 212°F (100°C) or more, replace ECM. If EGR gas temperature displayed on hand-held tester is less than 212°F (100°C), replace EGR temperature sensor.
Fig 1: Identifying EGR & EVAP Vacuum Switching Valve (VSV) Ports
G96B10182Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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