Why does the speedometer fluctuate up and down?
1 Answers
The speedometer fluctuates up and down due to a malfunction in the vehicle speed sensor. A faulty vehicle speed sensor can also cause unstable engine idle, momentary stalling or engine shutdown when starting or decelerating to stop while driving, as well as reduced engine acceleration performance. Here is more detailed information: The speedometer consists of two gauges: the speedometer and the odometer. The odometer is a digital instrument that calculates rotation through the engagement of components on the calculator's gear. It primarily obtains mileage signals from the speed sensor and can retain data even without power. The vehicle speed sensor is a device used to detect the speed of electronically controlled vehicles. The control computer uses this input signal to regulate engine idle speed, torque converter lock-up in automatic transmissions, automatic transmission gear shifting, engine cooling fan operation, cruise control, and other functions. The output signal from the vehicle speed sensor can be a magnetoelectric AC signal, a Hall-effect digital signal, or a photoelectric digital signal. The vehicle speed sensor is typically installed inside the drive axle housing or transmission case. The sensor signal wires are usually housed in shielded jackets to eliminate electromagnetic and radio frequency interference caused by high-voltage ignition wires, car phones, or other electronic devices.
