| CAUTION | If ECM replacement is instructed in following tests, always ensure ECM connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. |
Note. If DTCs P0110, P0115 and P0120 are output together, inspect ECM E2 circuit (sensor ground) between terminal No. 9 (Brown wire) at ECM harness connector E6 and splice I4. Repair as necessary. See WIRING DIAGRAMS article.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Intake Air Temperature (IAT) sensor is a thermistor built into MAF meter and is used to monitor temperature of 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 (built into MAF meter).
- 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.