Harley-Davidson FXDS-Conv Dyna Convertible Turn Signal Bulb Size
Harley-Davidson FXDS-Conv Dyna Convertible front turn signal bulbs measure 198 size while rear turn signal bulbs measure P21W size. The replacement chart covers 1994 through 1998 vehicle production 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 Harley-Davidson FXDS-Conv Dyna Convertible uses two distinct bulb types across its turn signal system for the 1994-1998 model years: the 198 at the front and the P21W at the rear.
The 198 bulb follows the ANSI standard, which governs lighting specifications in the United States and Canada. It is a T5 miniature wedge bulb rated at 12V and 2W, placing it among the lower-wattage bulb formats used in automotive signalling applications.
The T5 designation refers to the tubular glass envelope width, measured in eighths of an inch, making the 198 a notably small-format bulb. Its wedge base design means it requires no separate socket retainer, as the base itself locks into the housing by friction.
The rear turn signal uses the P21W, which conforms to the ECE standard used across Europe and much of the world. It operates at 12V and 21W, making it significantly higher in wattage than the front 198 bulb.
The P21W uses a BA15s bayonet base, where "BA15" denotes a 15mm bayonet cap and "s" indicates a single-contact configuration. This single-filament construction means the bulb serves one function only, in this case turn signalling, rather than combining multiple functions in one envelope.
The front 198 and rear P21W bulbs are not interchangeable. Their base types, wattage ratings, and governing standards are all different, and substituting one for the other would be incompatible with the respective housings.
The difference in wattage between the front and rear bulbs, 2W versus 21W, reflects a common practice in motorcycle lighting where rear signals are assigned higher-output bulbs to improve visibility from behind.
Both bulb sizes remain consistent across all five model years covered in the specifications, from 1994 through 1998, with no variation in either the front or rear fitment during that period.