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 Powertrain Control Module (PCM). The PCM applies 5 volts to the ECT sensor. The PCM 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 PCM will receive a high voltage input, and when the engine is warm the PCM 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 time to over 40℃ or the change of engine coolant temperature detected by ECT sensor is out of threshold, the PCM determines that a fault exists and a DTC is stored.
Item | Detecting Condition | Possible cause | |
DTC Strategy | Case 1 | ● Time(Tdf) from beginning up to 30℃ once to beginning over 30℃ again monitored. | ● Faulty ECTS ● Faulty PCM |
Case 2 | ● Temperature shifting is monitored | ||
Enable Conditions | Case 1 | ● Engine Speed > 1500rpm | |
Case 2 | ● Load Value > 25% | ||
Case 3 | ● Coolant at start > 7℃ | ||
Threshold value | Case 1 | ● Tdf > 300sec | |
Case 2 | ● I Wtmax - Wtmin I < 1℃ | ||
Diagnosis Time | ● 300sec Cumulative | ||
Temperature(℃/℉) | -33/-22 | -20/-4 | 0/32 | 20/68 | 40/140 | 60/140 | 80/176 | 100/212 | 110/230 |
Resistance(kΩ) | 26.74 | 15.48 | 5.79 | 2.45 | 1.148 | 0.587 | 0.322 | 0.188 | 0.147 |
Voltage(V) | 4.39 | 4.17 | 3.48 | 2.56 | 1.68 | 1.04 | 0.63 | 0.39 | 0.31 |
