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 (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.
Checking output signals from ECTS every 120 sec. under detecting condition, if an output signal is above 4.9V for more than 4 sec., PCM sets P1115.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● This code detects a intermittent open or short to battey in the signal circuit or the sensor | ● Poor Connection ● Open or short to battery in signal Circuit ● Open in Ground Circuit. ● Faulty ECTS ● Faulty PCM |
Enable Conditions | Case 1 | ● Engine Running Time > 120sec. |
Case 2 | ● Soak Time > 360min. ● Engine Running | |
Threshold value | ● Coolant signal > 4.9V | |
Diagnosis Time | ● Continuous (More than 4 sec. failure for every 120 sec. test) | |
MIL On Condition | ● DTC only (NO MIL ON) |
Temp. (°C/°F) | Resistance (kΩ) | Temp. (°C/°F) | Resistance (kΩ) |
-40(-40) | 48.14 | 40(104) | 1.15 |
-20(-4) | 14.13 ~ 16.83 | 60(140) | 0.59 |
0(32) | 5.79 | 80(176) | 0.32 |
20(68) | 2.31 ~ 2.59 |
