Harley-Davidson FLD Switchback Brake Bulb Size

The Harley-Davidson FLD Switchback uses a 3157 bulb size for brake applications. The replacement chart covers 2012 to 2016 model years with corresponding bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	US Type	EU Type	Shop
2012-2016	3157	P27/7W	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157	Check Price

Other Locations

Additional Notes

The Harley-Davidson FLD Switchback uses the 3157 bulb for the brake light position across all listed model years, spanning 2012-2016.
The 3157 is an ANSI-standardized bulb type recognized across the United States and Canada, meaning it conforms to a defined set of electrical and physical specifications shared by multiple manufacturers.
The 3157 is a dual-filament bulb, which means it contains two separate filaments within a single housing, one rated at 27W for the brake and turn signal function and one rated at 7W for the running light function.
The bulb operates on a 12V electrical system, consistent with standard automotive and motorcycle electrical architecture.
The 3157 follows the T25 wedge form factor, a designation that describes the shape and base type of the bulb housing used to seat it within the lamp assembly.
Because the 3157 is a dual-filament type, substituting it with a single-filament equivalent would result in the loss of one lighting function, making filament count a critical factor in replacement selection.