Service manual

G420F(FE) Service Manual Chapter 5. Engine Management System (EMS) 197
ECT (Engine Coolant Temperature)
Sensor
Component Location
Description
The 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 the rmistor 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 5 V in the
ECM 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.
Sensor Inspection
1. Remove the engine coolant temperature sensor
from the intake intake manifold.
2. With the temperature sensing portion of the
engine coolant temperature sensor immersed in
hot water, check resistance.
Temperature ℃ (℉) ECTS Resistance(kΩ)
-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
3. If the resistance deviates from the standard value
greatly, replace the sensor.