In brief, the bulb type for a third brake light depends on your vehicle. Common possibilities include P21/5W incandescent bulbs, dual-filament bulbs such as 1157, wedge-style bulbs like 194/168, or an integrated LED module. Many newer cars use LED third brake lights that are not user-replaceable and require replacing the entire unit.
In more detail, the third brake light sits at the top center of the rear of the vehicle and is designed to illuminate when you brake, increasing visibility for drivers behind you. The exact replacement path—bulb versus LED module or entire assembly—varies by make, model, and year. To avoid buying the wrong part, consult the owner's manual or an up-to-date parts lookup for your specific vehicle.
Identify the exact bulb or module for your vehicle
To determine the precise bulb type or replacement path for your third brake light, follow these steps:
- Check the vehicle's owner's manual or service manual for the bulb size or LED module part number specific to your model and year.
- Carefully remove the third brake light lens or access cover and look for markings on the bulb or module that indicate the size or type (for example, 194, 168, 1157, 7443, etc.).
- If markings aren’t visible, use a trusted online parts database or auto parts retailer’s bulb finder by entering year/make/model (and VIN if needed) to confirm the correct part.
- Determine whether your unit uses replaceable bulbs or is an LED module; LED-based third brake lights often require replacing the entire unit rather than a single bulb.
Following these steps helps ensure you purchase the correct part and perform a safe replacement.
Common bulb categories you might encounter
Across different generations, third brake lights fall into a few broad categories. Knowing these categories helps when shopping or planning a repair.
- Incandescent dual-filament bulbs (examples include 1157-type bulbs) used in some tail/stop circuits where one filament handles brake and the other handles tail light.
- Single-filament wedge bulbs (such as 194/168) used in some trunk-mounted or marker-style third brake lights.
- Larger dual-filament bulbs (such as 7443) used in certain rear-light assemblies and some third brake light placements.
- LED modules or LED light strips built into the third brake light housing; these are common in newer vehicles and often require replacing the entire unit rather than a separate bulb.
When planning a replacement, decide whether you want to stay with an incandescent bulb or upgrade to an LED option, and whether you’ll replace only the bulb or the full LED assembly. LED options can offer longer life and stronger illumination, but ensure compatibility with your vehicle’s electrical system and housing.
Summary
The exact bulb for a third brake light varies by vehicle. Start with the owner's manual or a current parts lookup for your year, make, and model, then inspect the unit to determine whether you need a replaceable bulb or a new LED module. If you’re unsure, consult a professional to ensure proper fit, safety, and legality in your region.