Why does the dashboard needle swing violently when starting the car?
2 Answers
The reason why the dashboard needle swings violently when starting the car is due to a weak battery. The causes of a weak car battery are: 1. Short driving distances leading to insufficient charging; 2. Prolonged use of high-power electrical devices; 3. Unclosed electrical appliances after locking the vehicle; 4. Poor battery quality resulting in insufficient power storage; 5. Short circuit, open circuit between battery poles, or loose connection at the battery terminals; 6. Vehicle leakage. The car dashboard is a device that reflects the working conditions of various vehicle systems, commonly including fuel indicator lights, washer fluid indicator lights, electronic throttle indicator lights, front and rear fog light indicators, and warning lights.
I've encountered many car owners complaining about erratic needle movements on the dashboard during startup, which is usually caused by unstable power supply systems. The ignition moment requires high current, and if the battery is aged or insufficiently charged, the voltage can drop significantly, causing needle fluctuations. Additionally, if the alternator malfunctions and fails to replenish power promptly, it can also cause voltage fluctuations. I've also noticed issues with contact points, such as loose or corroded battery terminals, or poor contact in the main circuit fuses, which can affect stability. I recommend checking the battery's lifespan immediately and using a multimeter to measure the voltage; it should be around 14 volts after normal ignition. If it's below 12 volts, the battery might need replacement. Don't underestimate this symptom, as it might mask engine starting weakness, and prolonged neglect could affect driving. It's best to have a professional shop conduct a comprehensive diagnosis to prevent the risk of roadside breakdowns.
