| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES - IMPORT article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Note. If DTCs P0100, P0101, P0110, P0115 and P0120 are output together, check circuit E2 (White wire) between terminal No. 18 at ECM harness connector E8 and splice E7. Repair as necessary. See WIRING DIAGRAMS article.
Note. For component location, see appropriate illustration in THEORY & OPERATION article.
Circuit Description
Engine Coolant Temperature (ECT) sensor is a thermistor sensor which monitors water 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.