The Engine Coolant Temperature(ECT) Sensor measures the temperature of engine coolant. The Engine Coolant Temperature (ECT) Sensor is located in the thermostat housing of the cylinder head. ECT Sensor is a thermistor (A Variable Resistor that Changes Along with ECT) in series with a fixed resistor in the Engine Control Module (ECM). The ECM applies 5 volts to the ECT sensor. The ECM monitors the voltage across the ECT sensor and converts it into a temperature reading. When the engine is cold the ECT sensor resistance is high, and when the engine is warm the ECT sensor resistance is low. Therefore, when the engine is cold the ECM will receive a high voltage input, and when the engine is warm the ECM will receive a low voltage input. The signal from ECT sensor is used for Injection, ignition timing, idle speed and cooling fan control.
If the difference between max.temp. and min. temp. is lower than 1℃(1.8℉), the ECM judged as a fault and DTC is set.
☞ Tdf is the elapsed time under 40℃(104℉) after over 40℃(104℉) once
Item | Detecting Condition | Possible cause |
DTC Strategy | ● Time(Tdf) is monitored (elapsed time under 40℃ after over 40℃(104℉) once) ● Temperature shifting is monitored | ● Poor connection ● Defective ECT Sensor ● Defective ECM |
Enable Conditions | ● Engine speed > 1500rpm ● Load value > 25% ● Coolant at start > 7℃(44.6℉) | |
Threshold value | ● Tdf > 300sec ● | Wtmax - Wtmin | < 1℃(1.8℉) | |
Diagnosis Time | ● 300 sec Continuous | |
MIL On Condition | ● 2 driving cycles |
