Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
- Connect scan tool to Data Link Connector (DLC) No. 3. See Figure. Start and warm engine to normal operating temperature. Using scan tool, monitor MAF flow rate. If scan tool reading is 0.0 gm/sec., go to next step. If scan tool reading is 271 gm/sec. or more, go to step 5.
- Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. Measure voltage between ground and Black/Yellow wire at MAF meter harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in Black/Yellow wire between EFI main relay and MAF meter. See WIRING DIAGRAMS article.
- Turn ignition off. Connect MAF meter harness connector. Access ECM behind glove box. 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 ground and terminal No. 10 (Blue/Yellow wire) at ECM harness connector E7. See Fig 1. If voltage is not .5-3.0 volts, go to next step. If voltage is .5-3.0 volts, replace ECM.
- Check for open or short in Blue/Yellow wire between MAF meter and ECM harness connector E7. 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. Using DVOM, backprobe ECM harness connector and measure resistance between ground and terminal No. 19 (Green/White wire) at ECM harness connector E7. See Fig 1. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, replace ECM.
- Check for open in Green/White wire between MAF meter and ECM harness connector E7. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.