The Triumph Thunderbird 1700 uses a PY21W bulb size for both front and rear turn signal applications. The replacement chart covers 2010 to 2011 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.
The PY21W is the sole bulb type specified for the Triumph Thunderbird 1700, covering both front and rear turn signal positions across the 2010-2011 model years.
The PY21W operates on a 12-volt electrical system and draws 21 watts, placing it in the standard single-filament category used widely in automotive turn signal applications.
The bulb produces amber light natively, meaning its glass envelope is tinted rather than relying on a colored lens to achieve the required turn signal color.
The PY21W uses a BAU15s bayonet base, which features offset pins to prevent incorrect installation. This base is distinct from the more common BA15s base, and the two are not interchangeable.
The PY21W is governed by ECE regulations, a standard recognized across Europe and numerous other markets worldwide, which defines its output, color, and base configuration.
Because the front and rear turn signal positions share the same PY21W specification on the Triumph Thunderbird 1700, a single bulb type serves all four turn signal sockets on the vehicle.