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.

Conditions required to set DTC are:

• Engine running time greater than 2 minutes.
• ECT sensor signal indicates -38°F (-37°C), about 5 volts, for 12 seconds over a 25-second period.