How can you determine if the brake lights are functioning correctly?

To determine if the brake lights are functioning correctly, the most reliable method involves having someone check the lights while the brake pedal is pressed. This approach allows for direct observation of the brake lights' activation in real-time, ensuring that they illuminate properly when the brake is engaged. It removes any ambiguity that might arise from visual inspections, which can miss issues like blown bulbs, poor connections, or wiring problems that affect functionality.

While visually inspecting the bulbs can provide information about their physical condition, it does not confirm whether they will light up when needed. Listening for sounds does not offer any direct evidence of brake light operation, making it an unreliable method. Observing the reactions of drivers behind you may provide anecdotal evidence of brake light functionality, but it is not a definitive method and can lead to misunderstandings if other factors influence driver behavior. Therefore, having someone assist during the brake pedal test is the most effective and practical technique to ensure brake lights are working as intended.