The Engine Coolant Temperature(ECT) Sensor measures the temperature of engine coolant. The Engine Coolant Temperature (ECT) Sensor is located near 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 control, ignition timing, idle speed and cooling fan control.
If measured temperature is higher than the maximum threshold value, ECM sets DTC P0117.(In this case, the input signal voltage is the minimum threshold vaue.)
Item
Detecting Condition
Possible Cause
DTC Strategy
Signal check, low
Poor connection
Short to ground in signal circuit
ECTS
Enable Conditions
-
Threshold Value
Measured temperature > 138.8 ?
Diagnostic Time
MIL ON Condition
3 driving cycle
Temperature [°C (°F)]
Resistance [kO]
-40(-40)
48.14
-20(-4)
14.13~16.83
0(32)
5.79
20(68)
2.31~2.59
40(104)
1.15
60(140)
0.59
80(176)
0.32