What Causes One Brake Light to Work While the Other Doesn't?

[MacMia]

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.