| 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 - TOYOTA article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Circuit Description & Possible Causes
DTC is set when ECM detects engine coolant temperature is less than 167°F (75°C) when engine should be at normal operating temperature. Possible causes are
- Defective cooling system thermostat.
- Defective ECT sensor.
- Defective ECM.