What Causes One Brake Light to Work While the Other Doesn't?
2 Answers
Reasons for one brake light working while the other doesn't: 1. It is very likely due to a burnt-out filament in the brake light. After prolonged use, aging is normal, which can cause the brake light to malfunction. In this case, it needs to be replaced promptly. 2. Of course, it could also be an issue with the wiring, which would require a professional to diagnose and fix. 3. Another possibility is a faulty brake light switch. Additional Information: A non-functioning brake light will cause the vehicle to fail the annual inspection. Current inspection standards are strict, and brake lights must be operational because one of the steps involves uploading a photo of the brake lights—if they don't work, the vehicle will not pass. Vehicle annual inspection refers to the mandatory testing required for all vehicles with official license plates and registration certificates. It is essentially an annual 'health check' for the vehicle, conducted in accordance with the 'Technical Conditions for Motor Vehicle Operation Safety,' to promptly identify and eliminate potential safety hazards, encourage proper vehicle maintenance, and reduce the likelihood of traffic accidents—commonly referred to as a vehicle inspection.
When encountering a situation where one brake light is on and the other is off, based on my experience driving many cars, the most common cause is that the bulb that's not lighting up has burned out—the filament is broken. It could also be due to poor contact in the bulb socket, such as dust or oxidation preventing current from passing. Replacing the bulb yourself is quite simple: buy a new bulb for a few dollars, pull out the old one, and plug in the new one. If it still doesn't light up after replacement, you need to check the fuse, as the dedicated fuse for that light might have blown. Wiring issues should not be overlooked either, such as aging wires or a short circuit affecting only one side. Safety first—don't take it lightly. Driving at night can be risky, so it's best to address the issue immediately or take it to a shop for inspection. Regularly replacing bulbs can prevent such minor faults.
