Circuit Description
WARNING: This page is about a different car, the 2003 Toyota Tacoma. However, it is still accessible from the selected car via links, so may be relevant.
A thermistor built into the engine coolant temperature sensor changes the resistance value according to the engine coolant temperature. The structure of the sensor and connection to the ECM is the same as in the IAT sensor circuit. 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 and then engine coolant temperature is assumed to be 176°F (80°C).