Plymouth Horizon front turn signal bulbs use 1157 or 2057NA size, while rear turn signal bulbs use 1157 or 1156 size. The replacement chart covers vehicle production years spanning 1978 to 1990.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 bulb is the dominant turn signal bulb across the Plymouth Horizon's production run, appearing in both front and rear positions for the majority of model years covered in these specifications.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve both turn signal and parking light functions simultaneously.
The 2057NA shares the same BAY15d bayonet base as the 1157 but draws higher wattage at 26.9W and 8W across its two filaments. Its natural amber glass produces a colored output without relying on a tinted lens or housing.
Because the 1157 and 2057NA share the BAY15d base, the 2057NA is physically interchangeable with the 1157 at the socket level, though the wattage difference may affect heat output and compatibility with certain housings.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. The BA15s base is not interchangeable with the BAY15d base used by the 1157 and 2057NA, as the two base types differ in pin alignment.
The Plymouth Horizon's front turn signal uses the 1157 for all model years except 1982, which specifies the 2057NA. This makes 1982 the sole model year with a natural amber front turn signal bulb in the front position.
The rear turn signal on the Plymouth Horizon uses the 1156 single-filament bulb for the 1978 and 1980 model years, while all other listed years use the dual-filament 1157. The socket base types differ between these two bulbs, so they are not directly interchangeable.
All three bulb types in these specifications conform to ANSI standards recognized in both the United States and Canada, indicating standardized electrical and physical tolerances across the bulb series.