Circuit Description

Engine Coolant Temperature (ECT) sensor is a thermistor or a variable resistor, that varies resistance based on temperature. As temperature of ECT sensor increases, resistance decreases. High temperature will result in a low signal voltage. ECT sensor value will be about 1.5-2.0 volts when the engine is fully warmed. DTC will set when PCM senses a continuous open in ECT sensor circuit.

Conditions required to set DTC are:

• Engine running time greater than 2.5 minutes.
• ECT sensor signal indicates -38°F (-39°C) or less (about 5 volts) for 12 seconds over a 25-second period.