Circuit Description

The engine coolant temperature (ECT) sensor is a variable resistor that measures the temperature of the engine coolant. The engine control module (ECM) supplies 5 volts to the ECT signal circuit and supplies a ground to the low reference circuit. If the ECM detects that the difference between the actual coolant temperature and the start-up coolant temperature is less than a threshold, this DTC sets.

The following table illustrates the difference between temperature, resistance, and voltage: