Fig. 2.184. Wiring diagram of the coolant temperature sensor with the ECU
The coolant temperature sensor is installed in the coolant pipeline on the cylinder head. It measures the coolant temperature and sends a signal to the engine control unit. The sensor is made in the form of a thermistor, sensitive to temperature changes. The electrical resistance of the sensor decreases with increasing temperature. The ECU determines the coolant temperature based on the value of the sensor signal voltage and sets the optimal enrichment of the working mixture when the engine warms up (Fig. 2.184).
Fig. 2.185. Immersion of the sensor in hot coolant
Immerse the sensor in hot coolant (Fig. 2.185).
Check if the sensor resistance is normal.
Sensor resistance:
- at 60°C: 123.8–172.8 Ohm;
- at 115°C: 23.5–29.5 Ohm.
Installation
Check that the thermostat is correctly installed in the housing and that its flange fits tightly against the housing at the installation location.
Install the coolant inlet pipe with a new gasket.
Fill the cooling system with clean coolant.
Coolant temperature sensor tightening torque: 20–40 Nm.