Harley-Davidson FLD Switchback headlight bulbs use 9003 size for both high and low beam functions. The replacement chart covers 2012 to 2016 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 FLD Switchback uses the 9003 bulb for both high beam and low beam headlight positions across the 2012-2016 model years.
The 9003 is an ANSI-standard halogen bulb recognized in the United States and Canada, operating on a 12-volt electrical system with a dual-filament design rated at 60 watts on high beam and 55 watts on low beam.
Because both headlight positions share the same 9003 specification, a single bulb type serves the entire headlight assembly on the FLD Switchback.
The 9003 bulb uses a P43t base, which is a bayonet-style mount with a 43mm collar. A bulb with a different base type is not a direct physical fit for this application, regardless of wattage or voltage compatibility.
The 9003 and H4 designations refer to the same physical bulb under different naming conventions, with 9003 being the ANSI designation and H4 being the ECE designation used in international markets.
The dual-filament construction of the 9003 means both the high and low beam functions are contained within one bulb envelope, which is why a single part number covers both headlight positions on the FLD Switchback.