Engine Coolant Temperature Sensor
The Engine Cooling Temperature (ECT) sensor is a Negative Temperature Coefficient (NTC) resistor. The ECT sensor allows the Powertrain Control Module (PCM) to monitor the engine coolant temperature.
The ECT sensor circuit consists of a voltage divider which incorporates a Negative Temperature Coefficient (NTC) resistor. The input to the ECT sensor is a 5V reference voltage supplied through a resistor within the PCM. The ground from the ECT sensor is also connected to the PCM which measures the voltage across the ECT sensor. As the engine coolant temperature rises the resistance of the ECT sensor decreases and vice versa. The PCM calculates the engine coolant temperature from a map of sensor voltage against temperature.
The ECT sensor is secured with a twist-lock and latch mechanism and is sealed with an o-ring. The ECT sensors are a push fit in the housing and rotated clockwise to lock in position. A 2-pin electrical connector provides the interface between the ECT sensor and the engine wiring harness.
The ECT sensor is located in the heater manifold, at the rear of the bank 1 cylinder head. The input from the ECT sensor is used in calibration tables and by other systems.
If the ECT sensor fails, the Powertrain Control Module (PCM) adopts an estimated coolant temperature. On the second consecutive trip with an ECT sensor fault, the PCM illuminates the Malfunction Indicator Lamp (MIL).