What Causes Instantaneous Power Loss and Recovery While Driving?
3 Answers
Instantaneous power loss and recovery while driving is typically caused by an issue with the alternator. The alternator may be malfunctioning due to problems with the carbon brushes or rectifier, in which case the entire alternator assembly needs to be replaced. Below are detailed explanations about automotive alternators: Introduction: The automotive alternator is the main power source of a vehicle. Its function is to supply power to all electrical devices (except the starter) while the engine is running normally (above idle speed) and simultaneously charge the battery. Composition: Based on the three-phase stator winding of a standard AC alternator, it increases the number of winding turns and adds lead-out terminals, along with an additional set of three-phase bridge rectifiers. At low speeds, the output is delivered by the original winding and the additional winding in series, while at higher speeds, only the original three-phase winding provides the output.
I've encountered this issue while driving too, and it was quite a scare when the steering wheel suddenly became heavy and the brakes wouldn't work. Later, when I had a mechanic check it, he said the most common cause for this is loose battery terminals, where road bumps cause poor contact that then suddenly restores. In my own car, the battery terminals were oxidized, and simply cleaning them and tightening them fixed the issue. Additionally, a slipping alternator belt or a faulty voltage regulator inside the alternator can also cause unstable power supply, as can poor fuse contact or aging wiring in older cars. I'd like to remind everyone that if this happens, you should immediately pull over, turn on your hazard lights, and never try to keep driving—safety is the top priority. Checking the issue isn't too difficult either; start with the battery connections, and if that doesn't solve it, take it to a professional repair shop to test the alternator's output voltage.
I fixed a similar issue myself last year. That day, while driving, the dashboard suddenly went completely black, then returned to normal after a second or two. After checking the repair manual, I found that there was a loose connection in the engine compartment wiring harness, causing intermittent power loss when vibrating. I spent half an hour under the car and found that a main harness connector was oxidized, leading to poor contact. Another common cause of this issue is the generator voltage regulator, which acts like a water valve—if it doesn't regulate properly, the current can fluctuate. Additionally, worn ignition switches in older Buick models can also cause power interruptions. I recommend using a multimeter to check the battery voltage during startup; if it's below 9 volts, it indicates a power supply problem. Remember, when the power is cut, both power steering and brake assist will fail, so stay calm.
