Which light bulb is the brake light?
The brake light is typically the brighter filament in a dual-filament rear-light bulb. For most cars, that means the standard 1157 bulb, though some models use 3157 or other dual-filament variants. In newer vehicles with LED taillights, the brake function is often provided by a dedicated LED module rather than a single replaceable bulb.
Brake lights are part of the taillight assembly and illuminate when you press the brake pedal. A dual-filament bulb houses two filaments: a dimmer filament for tail/run lights and a brighter filament for braking. The exact bulb type depends on the vehicle’s make, model, year, and market. Always verify with the owner's manual or by inspecting the current bulb markings or the bulb label inside the trunk.
Common dual-filament bulb types used for brake lights
To help identify replacements, here are the bulbs most often found in conventional bulb-based brake/taillight assemblies. The two-filament design means you typically replace one bulb to restore both functions.
- 1157: A classic 12V dual-filament bulb used in many passenger cars and light trucks. The dim filament powers the tail light, while the bright filament powers the brake light.
- 3157: A closely related dual-filament bulb used in some models; similar function but with a different base or mounting. Check fitment for your vehicle.
Note that some vehicles may use different dual-filament bulbs or, in newer designs, LED brake-light modules. Always confirm the exact bulb type for your car before buying.
How to identify and replace the brake light bulb in your vehicle
To identify the correct bulb and perform a replacement, follow these general steps. Some cars require accessing the rear light cluster from inside a trunk or behind a removable panel.
- Consult the owner’s manual or check the bulb markings to confirm the exact part number and base type (for example, 1157 or 3157).
- Inspect the rear light cluster or remove the lens/cover to determine whether the assembly uses a dual-filament bulb or a dedicated LED module.
- Purchase the correct replacement with the same base and dual-filament configuration if applicable, or replace the entire LED module if required by your vehicle.
- Safely replace the bulb, reassemble the lens, and test the brake lights by applying the brakes while the car is safely parked.
Conclusion: If your vehicle uses an LED brake-light module, you’ll typically replace the whole LED unit rather than a single bulb; otherwise, matching a dual-filament bulb such as 1157 or 3157 will restore brake-light function.
Summary
In most vehicles, the brake light is powered by the bright filament of a dual-filament rear light bulb—most commonly the 1157, with 3157 as a frequent alternative. Some models use different dual-filament bulbs, and newer cars may rely on LED brake-light modules. Always verify the correct type by checking the owner's manual or the bulb markings to ensure proper function and compliance.
