Note. For circuit reference, see the appropriate WIRING DIAGRAMS article. For connector and terminal identification, see CONNECTOR IDENTIFICATION .
Circuit Description
Engine Coolant Temperature (ECT) sensor is a thermistor which changes resistance based on temperature. ECT sensor is located in water pump housing. ECT sensor has a signal circuit and a ground circuit. PCM applies about 5 volts on signal circuit to sensor and monitors changes in this voltage caused by changes in resistance of sensor to determine coolant temperature.
When coolant is cold, sensor resistance is high and when coolant is warm, sensor resistance low. When PCM senses a signal voltage lower than normal operating range of sensor, DTC will set.
DTC will set when following conditions are present
- Engine operating more than 20 seconds.
- PCM indicates engine coolant temp more than 304°F (151°C).
- Conditions met for 4.5 seconds.