Why is the speed not displayed on the dashboard?
3 Answers
When the car dashboard does not display speed, it is usually due to a damaged speed sensor. Regular maintenance or part replacement: The car dashboard not displaying speed is caused by a damaged speed sensor. Vehicles require periodic maintenance or part replacement at certain mileage intervals. Without mileage data, it becomes difficult to diagnose. After a certain mileage, cars may need major repairs or even be phased out. Without mileage display, it's challenging to determine, so proactive measures must be taken. Vehicle speed calculation: The speedometer uses measurement signals from the speed sensor to calculate and display the vehicle's speed. There are two methods for calculating speed: one involves counting the number of pulses output by the sensor within a fixed time period, while the other measures the time taken for a fixed pulse cycle. In the pulse counting method, when the microprocessor detects an increase in pulse signals from the sensor, it begins counting pulses representing vehicle speed. After counting pulses for a preset duration, the counter data is compared with data in memory. If the difference reaches 1 km/h or more, the counter data is output to the display circuit to update the displayed value. This process continuously repeats.
After years of driving, the most common issue I've encountered with the dashboard speed not displaying is a faulty speed sensor. That thing is located near the wheels and can easily malfunction if it gets dirty or wet, failing to send signals. Another possibility is a stuck dashboard needle or a broken display unit—once it fails, the speed disappears. The fuse is also a potential culprit; if it blows, the entire circuit is interrupted. Driving on the highway without a speed display is nerve-wracking, making it easy to speed and get caught by cameras or even cause accidents. I recommend first checking the fuse box yourself and replacing it with one of the same specifications. If that doesn’t solve the problem, take it to a repair shop to replace the sensor or conduct a full inspection of the dashboard module. When washing your car, take the time to clean around the sensor to avoid many potential issues—don’t wait until there’s a problem to act.
My new car's speedometer malfunctioned right after purchase, leaving me frantic on the road. The mechanic diagnosed it as a common issue caused by a loose speed sensor connection—improperly secured wiring led to signal interruption, which he fixed simply by reseating it. Blown fuses are another frequent culprit; just locate and replace the corresponding fuse in the engine compartment's fuse box. For long trips encountering this issue, temporarily rely on a navigation app's speed display as an emergency workaround, but avoid prolonged dependence. The inspection method is straightforward: check under the car for detached or corroded sensor wires. Safety first—early intervention saves hassle.
