Can the automatic headlights remain on without turning them off after the engine is turned off?

[DelAniyah]

Yes. 'Auto' refers to the automatic headlights, which generally do not require manual intervention, and there is no need to turn them off when the engine is shut down. As long as there is sufficient light while driving, the system will automatically turn them off. However, automatic headlights can be quite sensitive at times, and if the owner finds this bothersome, they can also be manually turned off. The automatic headlights will control the switching on and off of the headlights based on the sensitivity to light levels. When 'Auto' is activated, it means the automatic headlights are in the 'on' state. The principle involves using electronic components such as photoresistors as sensors to send signals to the ECU, which controls the headlights' on/off function and the high/low beams. If the light suddenly dims while driving, the headlights will automatically turn on; if the light is sufficient, they will automatically turn off without requiring manual operation. Of course, because automatic headlights can be quite sensitive, they may sometimes turn on during the day. If the owner finds this troublesome, they can manually turn them off. After the car is turned off, if some electrical appliances are not switched off, they will continue to consume the battery's power. Once the car is turned off, the alternator stops working, and the only source of power for the entire vehicle is the battery. If some electrical devices are left on for an extended period, it can lead to battery depletion, shorten the battery's lifespan, and also affect the engine's ability to start.

[DiHannah]

I used to worry about this too, but after trying it, I realized how convenient automatic headlights are. After turning off the engine, you don’t have to do anything—the car cuts the power on its own, and the lights turn off after about half a minute. This design prevents battery drain from forgetting to turn off the lights, and even my wife, who always forgets, praises this thoughtful feature. However, note that some older models might not have this function, and luxury cars with a "follow-me-home" lighting feature may keep the lights on for a few extra minutes. Overall, 90% of new cars now support this, so you can just turn off the engine, lock the car, and walk away.

[StAlexander]

When designing automatic headlights, engineers already considered this issue. I've studied the circuit principles. When the car is turned off, the BCU control unit sends a command to cut power to the headlight relay, functioning like a smart switch. Some vehicles also incorporate light sensors—headlights turn off instantly when stopping during the day but may delay slightly at night. During my car modifications, I measured the current and found the power consumption within 30 seconds after shutdown to be negligible. The best part is this feature rarely fails unless the circuit has been modified. There's absolutely no need for manual operation—this is the core value of automatic headlights.

[VonMiranda]

A friend asked me the same question last time, and I had him try it out. Nowadays, mainstream car models indeed automatically turn off the lights when the engine is off, even if the key is not removed. However, there are two things to note: first, models with delayed light-off features (especially SUVs) will keep the lights on for a while after locking; second, cars with modified wiring might experience failures. My domestic car has been running for three years without manually turning off the lights, and the battery is still in good condition. In short, you don't need to worry about turning off the lights when the engine is off—it's a basic design logic.