What is the reason for the speedometer not working?
3 Answers
Most of the time, it is due to a damaged speed sensor, which requires repair. Below are some related extended information: 1. Speedometer: It actually consists of two gauges. One is the speedometer, and the other is the odometer. Traditional speedometers are mechanical. A typical mechanical odometer is connected to a flexible shaft, inside which there is a steel cable. The other end of the flexible shaft is connected to a gear in the transmission. The rotation of the gear drives the steel cable to rotate, which in turn rotates a magnet inside the speedometer's housing. 2. Odometer: The odometer is a digital instrument. It engages with the worm gear on the speedometer's drive shaft through the transmission gears of the counter drum, causing the counter drum to rotate. Its characteristic is that when the upper drum completes one full rotation, the lower drum rotates 1/10 of a turn. Like the speedometer, modern odometers also include electronic versions, which obtain mileage signals from speed sensors. The accumulated mileage data in electronic odometers is stored in non-volatile memory, allowing the data to be preserved even when there is no power.
I previously encountered an issue where the speedometer stopped working, mainly due to a faulty speed sensor. It's responsible for detecting wheel rotation and sending signals. If it gets dirty or damaged, the dashboard won't receive any data. Blown fuses are also quite common, especially in older cars, as a short circuit or excessive current can cause the fuse to blow, shutting down the entire system. Loose or oxidized electrical connections can also interrupt the signal, and since they're located under the chassis, they're prone to environmental damage. While a malfunctioning dashboard motor is rare, it still needs to be checked. Even though the car can still be driven with a non-functioning speedometer, inaccurate mileage records can affect maintenance schedules, such as confusing the oil change intervals based on incorrect mileage readings. It's recommended to start with the simplest solutions first—check the fuse box and try replacing the fuse. If that doesn’t work, take it to a professional shop to test the sensor output with specialized tools. Don’t delay too long to avoid escalating potential hazards.
When the odometer stops working, I always suspect an issue with the vehicle speed signal system, which may include sensor failure or wiring interruption. The sensors are located near the transmission or wheels, and dust or water accumulation can cause malfunctions. Modern cars are electronically controlled, and if the ECU doesn't receive the correct signal, it will cause the odometer to stop. Circuit board corrosion or blown fuses are also common, especially in humid environments. For self-inspection, check if the dashboard warning light is on, but avoid disassembling parts randomly. A non-functioning odometer can lead to inaccurate mileage records, raising suspicions of odometer tampering during car sales and affecting the price. Therefore, it's best to have a technician diagnose the issue early. The repair cost is usually low, but the key is to maintain the vehicle's reliability.
