General Information

Engine Coolant Temperature Sensor:

Temperature Vs Resistance Part 1:

Temperature Vs Resistance Part 2:

The Engine Coolant Temperature (ECT) sensor is located in the coolant bridge directly underneath the rear intake plenum switchover diaphragm (side of engine opposite the timing belt cover). The ECT sensor is used by the ECM for the base fuel control calculation, cooling fan(s) operation, EVAP purge solenoid control, EGR operation, ignition timing, oil life monitoring, idle speed control as well as many diagnostic trouble code enable functions. There is ONLY one engine coolant temperature sensor on this engine used to control the cooling fans, coolant temperature gauge and Coolant Temperature telltale.

The ECT sensor is a thermistor that changes resistance according to changes in engine coolant temperature. When the engine coolant temperature is low, the ECT sensor resistance is high (high signal voltage at ECM). As the temperature of the coolant increases, the sensor resistance decreases (lower signal voltage at ECM). The ECM supplies the sensor 5 volts through a pull-up resistor to the sensor, which is connected to ground. The ECM uses the voltage value on the signal line to determine engine coolant temperature. NOTE: the ECM uses only ONE pull-up resistor throughout the entire ECT sensor range.