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why does my speedometer jump
The internal failure of the instrument itself or the damage of the speed sensor, the short-circuit of the sensor circuit and the virtual connection, the damage of the gear ring.
The most conspicuous thing in the dashboard is the speedometer, which indicates the speed of the car in km/h. The speedometer actually consists of two tables, one is a speedometer and the other is an odometer.
The traditional speedometer is mechanical. A typical mechanical odometer is connected to a flexible shaft. There is a wire cable in the flexible shaft. The other end of the flexible shaft is connected to a gear of the transmission. The rotation of the gear drives the wire cable to rotate. A magnet in the odometer cover ring is driven to rotate. The cover ring is connected with the pointer and the pointer is set to the zero position through the hairspring. The speed of the magnet rotation causes a change in the size of the magnetic line of force, the balance is broken, and the pointer is therefore driven. This speedometer is simple and practical, and is widely used in various types of cars. With the development of electronic technology, electronic speedometers are now used in many car instruments. The common one is to obtain signals from the speed sensor on the transmission, and to deflect the pointer or display numbers through changes in the pulse frequency.
Odometer is a digital instrument. It uses the transmission gear of the counter drum to engage with the worm on the speedometer drive shaft to rotate the counter drum. Its characteristic is that the upper drum rotates a full circle, and the lower drum Cycle 1/10 times. Like the speedometer, the current odometer also has an electronic odometer, which obtains the mileage signal from the speed sensor. The mileage accumulated by the electronic odometer is stored in the non-volatile memory, and the data can be saved even when there is no electricity.
speedometer jump：
1:Idling speedometer bounce is generally caused by carbon deposits inside the throttle and idle motor, which can be solved by cleaning the throttle and idle motor;
2:The poor quality of gasoline results in poor atomization of the nozzle and insufficient combustion of the mixture in the cylinder, so it will also cause the speedometer to jump. It is recommended to use high-grade gasoline after using this tank of gasoline to clean the fuel system;
3:The spark plug does not ignite, which causes one or more cylinders to not work, and also causes the speedometer to jump. Check whether the ceramic part of the spark plug is cracked, and check whether the ignition module is normal.
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