What Causes a Complete Power Failure in a Car?
3 Answers
The reasons for a complete power failure in a car are: 1. Generator malfunction; 2. Battery depletion or terminal detachment; 3. Damage or burnout of the wiring from the battery to the fuse box; 4. Burnout or damage to the main circuit, main fuse, or main relay; 5. Faulty ignition switch. The solutions for a complete power failure in a car are: 1. Inspect and repair the generator; 2. Tighten the battery terminals and recharge the battery; 3. Check and repair the fuses, relays, and wiring; 4. Inspect or replace the ignition switch. Methods to prevent battery depletion include: 1. Turn off all electrical devices before parking; 2. Avoid frequent short-distance driving; 3. Regularly check the battery.
A couple of days ago, my neighbor Old Zhang's car experienced a complete power failure—the steering wheel locked up, and even the hazard lights wouldn't turn on, which really startled me. It was most likely the battery giving out completely, especially if it hadn't been replaced in five or six years—those are the ones most prone to sudden failure. Alternatively, the battery terminals might have oxidized to a whitish color, causing them to detach at the slightest touch. Once, while unpacking tools from the trunk, I found the main fuse box cover wasn’t properly closed, and the 30-amp fuse inside had melted into what looked like a broken piece of wire. Also, if the power cable for an aftermarket dashcam is incorrectly connected, it can short-circuit the entire vehicle’s electrical system. Most critically, if the alternator belt snaps, once the battery drains, the whole system can instantly shut down. In cases like this with a total power loss, you must call a tow truck immediately—never force the door open with the key.
My old car once had a complete power failure in the underground garage, even the central locking wouldn't work. The repair guy later said the battery was severely sulfated, with voltage dropping below 3 volts triggering protective shutdown. Another possibility is rodents chewing through main cables in the engine bay - I've seen forum posts where someone pulled half a nest of baby rats from wiring conduits. If you've modified audio power supply, incorrectly connecting high-power amplifiers can burn out main fuse. Voltage instability from generator rectifier bridge breakdown can also trigger power protection. In such cases, use mechanical key to open hood - always check fuse box for burnt smell before jump-starting.
