What is the fault when the brake light stays on after the car is turned off?

[McLyla]

Here is the fault analysis for when the brake light stays on after the car is turned off: 1. Lack of brake fluid: Brake fluid plays a crucial role in the car's braking system. When the driver steps on the brake pedal, the force applied is transmitted by the piston in the master cylinder through the brake fluid to the brake calipers at each wheel, causing the brake pads to contact the wheels and stop the vehicle. A lack of brake fluid can cause the brake light to stay on. 2. Damaged tail light bulb: The brake fluid reservoir has upper and lower lines. If the brake fluid in the reservoir is below the lower line, the sensor next to the reservoir will detect this and reflect it through the brake light on the dashboard. If the brake fluid level drops rapidly, it indicates a leak in the braking system. 3. Hand brake: Note that if you drive without releasing the hand brake, the light will also stay on. Therefore, check whether the hand brake is released.

[McAmir]

I've encountered this situation several times, and each time it was caused by a faulty brake light switch. Anyone who's driven for over a decade knows that if the brake lights stay on after turning off the engine, it's usually because the switch is stuck and hasn't reset. It might be jammed or excessively worn at the connection point under the brake pedal, so you should immediately check the switch and wiring for any short circuits or poor contact. Additionally, a relay malfunction could also keep the circuit powered. I recommend first gently wiggling the brake pedal to see if you can reset the switch. If that doesn't work, take it to a repair shop to replace the switch or relay. This issue can drain the battery quickly—last time, my battery died because the lights stayed on all night, making push-starting a real hassle. I also advise everyone to regularly clean dust and debris around the pedal to prevent the switch from sticking. Don't delay repairs—this problem not only wastes power but could also mislead drivers behind you into thinking you're braking, increasing the risk of a rear-end collision. Safety first!