Harley-Davidson FLHTCU Electra Glide Ultra Classic Tail Light Bulb Size

Harley-Davidson FLHTCU Electra Glide Ultra Classic tail light uses a 3157 bulb size. The replacement chart covers 2012 through 2019 production years with corresponding bulb 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	Bulb Size
2012-2019	3157

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157

Other Locations

Additional Notes

The 3157 is the tail light bulb size for the Harley-Davidson FLHTCU Electra Glide Ultra Classic across the 2012-2019 model years.
The 3157 is an ANSI-standardized bulb type, meaning its physical and electrical specifications are governed by a recognized North American standard used in both the United States and Canada.
This bulb follows the T25 wedge form factor, a designation that refers to its tubular shape and base style, which seats directly into a wedge-style socket without a separate metal base.
The 3157 operates on a 12-volt electrical system, consistent with standard automotive and motorcycle electrical architectures.
As a dual-filament bulb, the 3157 contains two separate filaments within a single envelope, rated at 27 watts and 7 watts respectively, allowing it to serve both a higher-intensity function and a lower-intensity function from one unit.
The higher 27-watt filament typically corresponds to braking or signaling output, while the lower 7-watt filament serves as a running or position light, making the 3157 suitable for combined tail and brake light applications.
The 3157 shares its base type with several related bulb numbers in the same family, such as the 3156, which is a single-filament variant. Substituting a single-filament type in a dual-filament application would result in the loss of one lighting function.