The Honda Motorcycle VTX1800C uses 12496 and PY21W bulb sizes for both front and rear turn signal applications. The replacement chart covers 2002 through 2008 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 Honda Motorcycle VTX1800C turn signal specifications reference two bulb types across its model years: the 12496 and the PY21W. Both operate at 12V, making them electrically compatible in terms of voltage.
The 12496 is a halogen bulb designated under Philips and Osram part numbering systems for specialty automotive applications. It is rated at 12V and is the more frequently specified bulb across the VTX1800C's front and rear turn signal positions.
The PY21W is defined under ECE (Economic Commission for Europe) standards and is used in markets worldwide. It is a single-filament amber bulb rated at 12V and 21W, fitted with a BAU15s offset bayonet base.
The BAU15s base of the PY21W features an offset pin arrangement, which physically prevents it from being inserted into sockets designed for the more common BA15s base. This makes the PY21W non-interchangeable with standard single-filament bulbs that share the same wattage but use a different base type.
For the front turn signal on the Honda Motorcycle VTX1800C, the 12496 is specified for 2003-2006 and 2008, while the PY21W is specified for 2002 and 2007. This means the front position does not use a single bulb type across all model years.
For the rear turn signal, the 12496 is specified for 2003, 2006-2008, while the PY21W is specified for 2002, 2004-2005. The rear position similarly alternates between the two bulb types depending on the model year.
In 2002, both the front and rear turn signal positions share the PY21W specification, making it the only year where a single bulb type covers both positions on the VTX1800C.
In 2007, the front turn signal specifies the PY21W while the rear specifies the 12496, meaning the two positions require different bulbs for that model year.
Because the 12496 is a specialty-application halogen bulb catalogued under manufacturer-specific part numbers rather than a universal ECE designation, sourcing it typically requires referencing Philips or Osram product lines directly.
Substituting a PY21W in a socket specified for the 12496, or vice versa, carries a risk of fitment incompatibility due to potential differences in base configuration, even though both bulbs share the same operating voltage.