What causes the speedometer to sometimes work and sometimes not?

[DamianDella]

Here are the specific methods for diagnosing a speedometer that intermittently works and stops: 1. Check if the vehicle speed sensor is damaged, inspect whether the sensor connector has a loose connection, examine if there are faults in the sensor's drive mechanism, and verify if there are any fault codes in the vehicle's wheel speed sensor and ABS control unit system. 2. The fault may be caused by the speedometer itself inside the instrument cluster or a loose connection of the instrument cluster connector. The instrument cluster can be diagnosed using a fault diagnostic tool to retrieve fault codes or perform an action test to determine if the issue lies with the speedometer itself. 3. The speedometer indicates the vehicle's speed via a needle pointer, displaying instantaneous speed rather than the total mileage. The speedometer's indication relies on the vehicle speed sensor, which is typically installed on the transmission.