Freightliner 114SD front turn signal bulb size is 3157NA and rear turn signal bulb size is 1157. Replacement chart covers 2012 to 2018 production years with bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Freightliner 114SD front turn signal uses the 3157NA bulb across all listed model years, spanning 2012-2018.
The 3157NA is a dual-filament T25 wedge bulb rated at 12V with a 27W high filament and 7W low filament, allowing it to serve both turn signal and parking light functions from a single housing.
The "NA" suffix in the 3157NA designation denotes natural amber glass, meaning the bulb produces an amber output without relying on a colored lens to achieve the required turn signal color.
The 3157NA carries ANSI standardization, making it a recognized specification in both the United States and Canada.
The rear turn signal on the 114SD uses the 1157 bulb, which is also a dual-filament design but features a BAY15d bayonet base rather than a wedge-style base, making the two bulb types physically non-interchangeable despite sharing the same 12V operating voltage.
The 1157 is rated at 21W for its high filament and 5W for its low filament, both figures lower than the corresponding filaments of the 3157NA, reflecting different luminous output requirements between front and rear positions.
The BAY15d bayonet base of the 1157 has two offset pins, a design that prevents incorrect insertion and ensures consistent filament alignment within the socket.
Because the 3157NA uses a wedge base and the 1157 uses a bayonet base, the front and rear turn signal sockets on the 114SD are not compatible with each other, and the bulb types are not interchangeable between positions.