Why does the tachometer stop working but the car can still run?

[LaHeidi]

The tachometer stops working but the car can still run because there is a malfunction in the speedometer of the vehicle's instrument cluster; the vehicle's wheel speed sensor has failed; the vehicle's mileage sensor has malfunctioned, or there is foreign matter stuck inside the gauge preventing movement. Removing the gauge and clearing the foreign matter can resolve the issue. Below is additional information about the tachometer: 1. Working principle: The tachometer is generally located within the instrument panel, symmetrically placed alongside the speedometer. It operates based on magnetic principles, receiving pulse signals generated when the primary current in the ignition coil is interrupted, and converts these signals into a displayable speed value. 2. Engine speed: The level of engine speed relates to the number of work cycles per unit time or the effective power output of the engine, meaning the engine's effective power varies with different speeds. Therefore, when specifying the engine's effective power, the corresponding speed must also be indicated. 3. Relationship: The faster the engine speed, the more pulses the ignition coil generates, resulting in a higher displayed speed value on the tachometer.