Hyundai Santa Fe (TM): Engine Control System / Engine Coolant Temperature Sensor (ECTS). Description and operation
Engine Coolant Temperature Sensor (ECTS) is located in the engine coolant passage
of the cylinder head for detecting the engine coolant temperature. The ECTS
uses a thermistor whose resistance changes with the temperature.
The electrical resistance of the ECTS decreases as the temperature increases,
and increases as the temperature decreases. The reference +5V is supplied to
the ECTS via a resistor in the ECM. That is, the resistor in the ECM and the
thermistor in the ECTS are connected in series. When the resistance value of
the thermistor in the ECTS changes according to the engine coolant temperature,
the output voltage also changes.
During cold engine operation, the ECM increases the fuel injection duration
and controls the ignition timing using the information of engine coolant temperature
to avoid engine stalling and improve drivability.

Inspection
1.
Turn the ignition switch OFF.
2.
Disconnect the IATS connector.
3.
Specification
Temperature [°C (°F)]
Resistance (kΩ)
-40 (-40)
41.74 - 54.54
-30 (-22)
23.
Other information:
Removal
1.
Disconnect the negative (-) battery terminal.
2.
Remove the crash pad lower pannel.
(Refer to Body - "Crash Pad Lower Panel")
3.
Loosen the mounting screw and remove the crash pad garnish [LH] (A).
System Block Diagram
Component Parts And Function Outline
Component part
Function
Vehicle-speed sensor, ESP/ABS Control Module
Converts vehicle speed to pulse.
ECM
Receives signals from sensor and control switches.