| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. On models equipped with engine immobilizer, if ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. If DTCs P0100, P0101, P0110, P0115 and P0120 are output simultaneously, the E2 sensor ground circuit at terminal No. 18 (Brown wire) at ECM electrical connector E5 may be open. See WIRING DIAGRAMS article. For ECM electrical connector terminal identification see scheme 4 It may be necessary to check Brown wire between splice I2 and terminal No. 18 at ECM electrical connector E5. Splice I2 is located behind passenger's side of instrument panel. (Scheme 308)
Circuit Description
Intake Air Temperature (IAT) sensor is a thermistor built into Mass Airflow (MAF) meter and is used to monitor temperature of intake air flowing through MAF meter. DTC is set when ECM detects an open or short in IAT sensor circuit. If DTC P0110 exists, ECM will operate in fail-safe mode in which intake air temperature is assumed to be 68°F (20°C). Possible causes are
- IAT sensor circuit is open or shorted.
- Defective IAT sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0110, use Toyota hand-held tester or scan tool to access CURRENT DATA to read the intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), IAT sensor circuit may be open. If displayed intake air temperature is 284°F (140°C) or more, IAT sensor circuit may be shorted. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.
Scheme 308
- Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 1 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 upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. ECM is located behind passenger's side kick panel, just below instrument panel. see scheme 2
- Turn ignition off. Disconnect electrical connector at MAF meter. MAF meter is bolted to upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. Connect jumper wire between terminals No. 4 (Red/White wire) and No. 5 (Brown wire) on electrical connector for MAF meter. see scheme 5
- 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 and passenger's side kick panel (if necessary) for access to ECM with electrical connectors still installed on ECM. see scheme 2 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 (Brown wire) at ECM electrical connector E5 and No. 23 (Red/White wire) at ECM electrical connector E4 with all electrical connectors installed on ECM. see scheme 4 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 Brown wire or Red/White wire between MAF meter and ECM. 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 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 and passenger's side kick panel (if necessary) for access to ECM with electrical connectors still installed on ECM. see scheme 2 Disconnect ECM electrical connectors E4 and E5. see scheme 4 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.