Triumph Daytona 900 Brake Bulb Size

The Triumph Daytona 900 brake bulb uses a P21/5W size for replacement applications. The replacement chart covers vehicle production spanning 1994 to 1996.

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
1994-1996	P21/5W

Bulb Specifications

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

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Additional Notes

The P21/5W is the brake bulb type specified for the Triumph Daytona 900 across the 1994-1996 model years.
P21/5W is an ECE-standard bulb recognized across European and worldwide markets, operating on a 12-volt system with a dual-filament design rated at 21 watts and 5 watts respectively.
The higher 21W filament serves the brake signal function, while the lower 5W filament handles a secondary role such as a running or position light, both contained within a single bulb housing.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d prevents incorrect insertion, ensuring the two filaments are connected to the correct circuits.
Because the BAY15d base is offset, it is not interchangeable with the BA15d base, which shares the same physical size but uses symmetrically placed pins and carries no filament polarity distinction.