| WARNING | Read service precautions before proceeding with service procedure. See SERVICE PRECAUTIONS . |
| 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. |
Note. If DTCs P0110, P0115 and P0120 are output simultaneously, the E2 sensor ground circuit at terminal No. 18 (Brown wire) at ECM electrical connector E8 may be open. See WIRING DIAGRAMS article. For ECM electrical connector terminal identification (Схема №7) It may be necessary to check Brown wire between splice I7 and terminal No. 18 at ECM electrical connector E8. Splice I7 is located behind passenger's side of instrument panel. (Схема №10)
Circuit Description
Engine Coolant Temperature (ECT) sensor is a thermistor sensor which monitors engine coolant temperature. DTC is set when ECM detects an open or short in ECT sensor circuit. If DTC P0115 exists, ECM will operate in fail-safe mode in which engine coolant temperature is assumed to be 176°F (80°C). Possible causes are
- ECT sensor circuit is open or shorted.
- Defective ECT sensor.
- Defective ECM.
Diagnostic Aids
After confirming DTC P0115, use Toyota hand-held tester or scan tool to access CURRENT DATA to read the engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), ECT sensor circuit may be open. If displayed engine coolant temperature is 284°F (140°C) or more, ECT 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.