tachometer drops to zero while driving

• 2021-12-30

For ordinary gasoline vehicles, even if the vehicle is stopped, the engine will maintain a speed of about 800 rpm to overcome the internal resistance of the engine. But recently, a friend said that his car's tachometer doesn't turn but can drive. So what is the reason for this problem?

During driving, the tachometer pointer often drops to zero suddenly. This is because the crankshaft position sensor is broken or the plug is falsely connected. If you can't handle the hairpin of the crankshaft position sensor, you can directly replace the sensor. The crankshaft position sensor is not work. It is recommended to go to the repair shop or 4S store to check and replace the sensor with a new one.

It may be caused by poor contact of instrument speed signal line. The speed sensor is a sensor that converts the speed of a rotating object into power output. The speed sensor is an indirect measuring device, which can be manufactured by mechanical, electrical, magnetic, optical and hybrid methods. According to different signal forms, speed sensors can be divided into analog and digital. Most of them output pulse signals (approximate sine wave or rectangular wave). The methods of measuring speed for pulse signals are: frequency integration method (It is the F / V conversion method, the direct result is voltage or current), and frequency operation method (the direct result is digital).

In automation technology, rotational speed is often measured, and linear speed is often measured indirectly by rotational speed. The DC tachogenerator can convert the rotating speed into an electrical signal. The tachometer requires a linear relationship between output voltage and speed, large output voltage steepness and good time and temperature stability.

The tachometer and speedometer are all reset to zero, but the driving is normal. When you are cruising at a constant speed at high speed, turn off the engine and restart. If the fault persists, try to disconnect the battery and connect it back. If it is normal, it is OK. Or check whether the negative electrode of the battery is oxidized. If not, replace the battery.

The speed indicator is an instrument that reflects the working conditions of the vehicle engine. It can reflect the current working frequency of the engine, which is generally expressed in rpm. The maximum speed of ordinary cars ranges from 6000-11000 rpm, while the maximum speed of trucks is only about 3000-5000 rpm. The speed pointer can help the driver master the correct shift timing and keep the vehicle in the most efficient working condition through speed control.