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Diagnosis & Repair

WARNING: This page is about a different car, the 2002 Toyota Sequoia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3 at driver's side of instrument panel. See Figure. Turn ignition on and then turn hand-held tester or scan tool on. Start engine and allow engine to idle. Using hand-held tester or scan tool, monitor MAF meter air flow rate. If MAF meter air flow rate is 0.0 gm/sec., go to next step. If MAF meter air flow rate is 271 gm/sec. or more, go to step  5.
  2. Turn ignition off. Disconnect electrical connector at MAF meter. MAF meter is bolted to top side of air intake hose, near upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 3 (Green/Red wire) on MAF meter electrical connector. See Fig 1. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in Green/Red wire between EFI main relay, EFI No. 2 fuse (10-amp) and MAF meter. See WIRING DIAGRAMS article. EFI main relay may also be referred to as EFI relay. EFI main relay and EFI No. 2 fuse are located in fuse/relay box at driver's side front corner of engine compartment.
  3. Turn ignition off. Reinstall electrical connector at MAF meter. Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. See Figure. Ensure A/C switch is in OFF position and shift lever is in Park or Neutral. Start engine and allow engine to idle. Using voltmeter, check voltage between body ground and terminal No. 10 (Red/White wire) at ECM electrical connector E7. See Figure. This is the VG terminal on ECM. Voltage should be .5-3.0 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
  4. Check for open and short in Red/White wire and electrical connectors between MAF meter and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace MAF meter. See AIRFLOW METER under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If wiring harness or electrical connector is defective, repair as necessary.
  5. Turn ignition off. Remove glove box and heater duct (if necessary) for access to ECM with electrical connectors still installed on ECM. See Figure. Using ohmmeter, check resistance between body ground and terminal No. 19 (Black/White wire) at ECM electrical connector E7. See Figure. The is the EVG terminal on ECM. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, replace ECM.
  6. Check for open in wiring harness and electrical connectors between MAF meter and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace MAF meter. See AIRFLOW METER under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If wiring harness or electrical connector is defective, repair as necessary.
    Fig 1: Identifying Mass Airflow Meter Electrical Connector Terminals
    G95I31375Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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