Circuit Description

WARNING: This page is about a different car, the 2000 Isuzu Rodeo and 2000 Isuzu Amigo. However, it is still accessible from the selected car via links, so may be relevant.

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.