Engine Coolant Temperature (ECT) Sensor

Sensor transmits an engine temperature signal to ECM. ECM sensor is a Negative Temperature Coefficient (NTC) type. ECM sensor receives a 5 volt reference signal from ECM trough a one kohm resistor integrated in ECM. ECT then returns a varying voltage depending on engine coolant temperature. If ECT sensor indicates that engine coolant temperature is lower than 19.4°F (-7°C), ECM will stop specific diagnosing procedure. If ECT sensor indicates that engine coolant temperature is higher than 140°F (60°C), ECM will start specific diagnosing procedure. If ECT sensor information is faulty, ECM defaults to a substitute temperature value equal to engine coolant temperature on start-up. It then increases that value by 1.8°F (1°C) for every 60 grams of air passing through the Mass Air Flow (MAF) sensor until a value equal to 194° (90°C) is reached. ECM uses ECT sensor information to control fuel injection duration and correct idle speed.