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:
Components and components location
Component Location
1. Engine room
relay box
2. Sub relay
box
3. ICU Junction
block
4. ICM relay
box
Relay Box (Engine Compartment).
Description
The ambient temperature sensor is located at the front of the condenser and
detects ambient air temperature. It is a negative type thermistor; resistance
will increase with lower temperature, and decrease with higher temperature.