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 uses a signal circuit and a ground circuit. PCM applies voltage (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 is low. When PCM senses a signal voltage higher than normal operating range of sensor, DTC will set.
- Engine operating more than 20 seconds.
- PCM indicates engine coolant temp less than -40°F (-40°C).
- Conditions met for 4.5 seconds.