Diagnosis & Repair
- 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.
- Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), go to next step. If displayed intake air temperature is 284°F (140°C) or more, go to step 8. If displayed intake air temperature is the same as actual air intake temperature, problem is intermittent. Check for defective connections or intermittent problem in wiring between MAF meter and ECM. 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. ECM is located at passenger's side of instrument panel, just below glove box. See Figure.
- 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. Connect jumper wire between terminals No. 4 (Blue/Yellow wire) and No. 5 (Brown wire) on electrical connector for MAF meter. See Figure.
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is less than 284°F (140°C), go to next step. If displayed intake air temperature is 284°F (140°C) or more, check for defective electrical connections at MAF meter and electrical connector. If electrical connections are defective, repair as necessary. If electrical connections are okay, replace MAF meter.
- Turn ignition off. Remove jumper wire. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Ensure electrical connectors at ECM are securely installed so all terminals in electrical connectors are contacting terminals in ECM.
- Ensure electrical connector at MAF meter is still disconnected. Connect jumper wire between terminal No. 18 (White wire) and No. 22 (Blue/Yellow wire) at ECM electrical connector E11 with all electrical connectors installed on ECM. See Figure. This is the E2 and THA terminals on ECM.
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is 284°F (140°C) or more, repair open in Blue/Yellow wire or Brown and White wire or between MAF meter and ECM. The Brown wire changes to a White wire at splice E4. Splice E4 is located near firewall. See Fig 1. See WIRING DIAGRAMS article. If displayed intake air temperature is not 284°F (140°C) or more, replace ECM.
- 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 hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is not -40°F (-40°C), go to next step. If displayed intake air temperature is -40°F (-40°C), replace MAF meter.
- Turn ignition off. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Disconnect ECM electrical connector E11. See Figure. Ensure electrical connector is still disconnected at MAF meter.
- Turn ignition on. Using hand-held tester or scan tool, read intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), repair short in wiring harness and electrical connectors between MAF meter and ECM. See WIRING DIAGRAMS article. If displayed intake air temperature is not -40°F (-40°C), replace ECM.
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