Attention! On models with gasoline engines with air conditioning and on models with diesel engines, the temperature sensor "Bitron" controls the coolant temperature gauge.
Examination
1. Temperature sensor "Bitron" (indicated by an arrow) screwed into the left side of the cylinder head. The sensor can be identified by the blue color of the electrical connector. On models 1.8 and 2.0 liters with 16 valves, the sensors are screwed into the thermostat housing.
2. The coolant temperature gauge is powered by a constant voltage from the instrument panel (through the ignition switch and fuse). Sensor "Bitron" installed in the ground circuit of the temperature gauge. The sensor contains a thermistor - an electronic component whose electrical resistance decreases according to a certain law as its temperature increases. When the coolant is cold, the resistance of the sensor is large, and as a result, the electric current through the temperature gauge is negligible and the arrow of the gauge points to blue (cold) section of the scale. With an increase in the temperature of the coolant and a decrease in the resistance of the sensor, i.e. increase in electric current, the pointer moves to the top of the scale. If the sensor is defective, it must be replaced.
3. On models with an over-temperature alarm lamp, the lamp is powered from the instrument panel and controlled by an instantaneous switch that is installed in the wire circuit connecting the lamp to ground. If the overtemperature alarm lamp is installed in addition to the temperature gauge, they are connected to the vehicle ground with two separate wires through the sensors.
4. If the temperature gauge shows an excess of temperature, and the light does not light up, then it is necessary to check the voltage supply to it and the sensor's performance. Perhaps the fault is in the conductor of the printed circuit board. The fault can be identified as follows.
5. If the temperature gauge needle is in the cold zone of the scale when the engine is hot, remove the wire from the sensor and attach it to the cylinder head. If the pointer arrow deviates when the ignition is turned on, then the sensor is faulty and must be replaced. If the arrow does not deviate, remove the dashboard and check the integrity of the wire between the sensor and the temperature gauge. If the wire is intact, and the defect is present, then the temperature gauge is faulty, which must be replaced.
6. If the temperature gauge needle points to a hot section of the scale when the engine is cold, remove the wire from the sensor. If the pointer needle returns to the cold part of the scale when the ignition is on, then the sensor is faulty and must be replaced. If the pointer still remains in place, check the electrical circuit as described earlier.
7. The operation of the emergency overtemperature lamp is checked in the same way.
Removing
The removal procedure is similar to removing the temperature sensor for turning on the radiator fan.