Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Highlander. However, it is still accessible from the selected car via links, so may be relevant.
- Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. 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.
- Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. Measure voltage between terminals No. 1 (Black/White wire) and No. 5 (White wire) at MAF meter harness connector. See Fig 1. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, go to step 7.
- Turn ignition off. Connect MAF meter harness connector. Access ECM behind glove box. See Figure. Ensure shift lever is in Neutral or Park. Ensure A/C switch is OFF. Start engine and let idle. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 12 (Yellow/Green wire) and No. 18 (White wire) at ECM harness connector E8. See Figure. If voltage is not .5-3.0 volts, go to next step. If voltage is .5-3.0 volts, replace ECM.
- Turn ignition off. Check for open or short in wiring between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.
- Turn ignition off. Access ECM behind glove box. See Figure. Using DVOM, backprobe ECM harness connector and measure resistance between terminals No. 18 (White wire) and No. 21 (Red/Black wire) at ECM harness connector E8. See Figure. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, replace ECM.
- Check for open or short in wiring between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.
- Turn ignition off. Disconnect negative battery cable. Access ECM behind glove box. See Figure. Disconnect ECM harness connectors E8. See Figure. Remove EFI relay from engine room junction box. Engine room junction box is located on driver's side of engine compartment. Measure resistance in Black/White wire between terminal No. 1 at MAF meter harness connector and socket No. 3 of EFI relay in engine room junction box. See Fig 1 and Fig 2 . If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, repair open in Black/White wire.
- Measure resistance of White wire between terminal No. 5 at MAF meter harness connector and terminal No. 18 at ECM harness connector E8. If resistance is one ohm or less, check ECM power source circuit. If resistance is greater than one ohm, repair open in White wire.