The Ford Five Hundred brake light utilizes 3157 and 4057 bulb sizes depending on the specific version of the vehicle. Data for the lighting components covers the range from 2005 to 2007.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford Five Hundred uses three distinct bulb sizes across its brake light positions: 4057, 3157, and 921, all of which conform to ANSI standards recognized in both the United States and Canada.
The 4057 and 3157 are both dual-filament wedge bulbs built to the T25 form factor, operating at 12V with a 27W/7W power rating, where the higher wattage filament serves the brake function and the lower wattage filament serves a secondary function such as running or tail light operation.
The 921 is a single-filament wedge bulb built to the T15 form factor, rated at 12V and 16W, and is used exclusively in the Center High Mount Stop Light position across all three model years covered by these specifications.
Although the 4057 and 3157 share identical voltage and wattage ratings as well as the same T25 wedge form factor, they are not the same part number and are not listed as interchangeable within these specifications.
The Ford Five Hundred (2006-2007) uses the 4057 bulb for the brake light position, while the 2005 model year uses the 3157 for that same position, indicating a fitment difference between the earlier and later production years.
The T25 wedge base is a larger wedge format than the T15, meaning the 921 used in the Center High Mount Stop Light is physically smaller than either the 4057 or 3157 used in the standard brake light positions.
The dual-filament design of the 4057 and 3157 allows a single bulb to serve two lighting functions within one housing, which is a common arrangement in combined tail and brake light assemblies.