Diagnosis & Repair
- Connect scan tester to DLC-3 connector. See Figure. Start vehicle engine and allow to idle. Turn on scan tester. Monitor MAF flow rate. If scan tester reading is 0.0 gm/sec., go to next step. If reading is 9.0-21.0 gm/sec. once engine is at normal operating temperature, go to step 5.
- Disconnect MAF harness connector. Ensure ignition is on. Using DVOM, measure voltage between terminal No. 1 and ground. See Fig 1. If 9-14 volts is present, go to next step. If 9-14 volts is NOT present, inspect circuit between MAF harness connector and ECM. See wiring diagram in WIRING DIAGRAMS
article. Repair as needed.
- Access ECM behind glove box. Start engine. Backprobing ECM connector, check voltage between terminal "VG" and ground. See Fig 2. If voltage is 1.1-1.5 volts, replace ECM and retest.
- If voltage is NOT 1.1-1.5 volts, check for open or short circuit between MAF and ECM. See wiring diagram in WIRING DIAGRAMS
article. Repair as needed. If circuit is okay, replace MAF sensor and retest.
- Access ECM behind glove box. Turn ignition off. Using ohmmeter, backprobe ECM harness connector. Check continuity between terminal "VG-" and ground. See Fig 2. If continuity does NOT exist, replace ECM and retest. If continuity does exist, check for open circuit between MAF sensor and ECM. See wiring diagram in WIRING DIAGRAMS
article. Repair as needed. If circuit is okay, replace MAF sensor.
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002