Figure 3.80. Location on the thermostat housing of the sensor (1) coolant and fitting temperatures (2) to remove air
This system is equipped with a single coolant temperature sensor that provides a signal to the fuel injection system control unit, the electric fan and the coolant temperature gauge in the instrument cluster.
System operation
Sensor 244 informs the injection system control unit of the coolant temperature. With this in mind, the injection system and the turntable of the fans of the engine cooling system are controlled.
- The electric fan unit turns on at low speed when the coolant temperature is above 99°C and turns off when the temperature falls below 96°C.
- The electric fan unit turns on at high speed when the coolant temperature is above 102°C, and turns off when the temperature drops below 100°C.
- The electric fan unit can be turned on at a high speed to prevent overheating and at a low speed when the air conditioner is running.
Engine overheating indicator
The indicator turns on by the electronic control unit of the injection system if the temperature of the coolant becomes higher than 120°C.
The sensor is installed in the thermostat housing (see Figure 3.80). It is a resistor with a negative temperature coefficient of resistance, i.e. as the temperature of the liquid rises, the electrical resistance of the sensor decreases (tab. 3.6).
Table 3.6. Dependence of resistance of sensors on temperature
Checking order:
- if the arrow of the coolant temperature gauge in the instrument cluster shows a low temperature all the time, although the engine is warm, disconnect the connector from the sensor and connect it to «mass» - the metal part of the engine. With the ignition on, the arrow should move to the high temperature area on the instrument. Otherwise, the defective sensor must be replaced. If the arrow does not move and when connecting the wire to «mass», remove the Dashboard as described in section «Body», and check the condition of the circuit between the sensor connector and the instrument, as well as the power supply to the instrument. If the circuit is working and voltage is supplied, the device is faulty, it must be replaced;
- if the gauge needle shows a high temperature when the engine is cold, disconnect the connector from the sensor. If the arrow returned to the low temperature area with the ignition on, the sensor is faulty. If the arrow does not deviate in this case, check the condition of the circuit as described earlier.
Removing
- drain part of the coolant as described above;
- Disconnect the connector and unscrew the sensor.
Installation is carried out in the reverse order of removal, apply sealant to the thread of the sensor.