1. Road condition: Uneven, uneven or damaged road surface will cause the speed measuring instrument to shake. When the vehicle runs on the uneven road surface, the speedometer will shake due to the vibration of the road surface.
2. Vehicle problems: Vehicle problems, such as unstable suspension system, unbalanced tires, brake system failure, etc., will cause the speedometer to shake.
3. Problems with speed measuring instruments: The quality or calibration problems of the speed measuring instruments themselves lead to jitter. There is something wrong with the sensor or measuring system of the speed measuring instrument, which will lead to inaccurate or unstable speed measuring results. Jitter refers to the instability, vibration or tremor of an object or system in the process of movement or operation. Indicates the rapid change or fluctuation of the position, speed, force or other physical quantities of an object or system. Jitter may be periodic, random or caused by other factors.