Triumph Scrambler Tail Light Bulb Size

The Triumph Scrambler tail light requires a P21/5W bulb size for proper illumination. The replacement chart covers 2006 through 2017 model 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
2006-2017	P21/5W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W

Other Locations

Additional Notes

The Triumph Scrambler uses the P21/5W bulb for the tail light across the 2006-2017 model years.
The P21/5W is a dual-filament bulb, with one filament rated at 21 watts for braking or turn signal functions and a second filament rated at 5 watts for the running light function.
The P21/5W operates on a 12-volt electrical system, consistent with standard motorcycle electrical architecture.
The bulb uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d base prevents incorrect single-filament bulbs from being seated in the socket.
The P21/5W conforms to ECE regulations, a standard recognized across Europe and numerous other markets worldwide.
Because the BAY15d base is specific to dual-filament applications, a single-filament BAY15s bulb is not a compatible substitute for the Triumph Scrambler tail light socket.