The Freightliner FL50 front turn signal requires a 1156 bulb size while the rear turn signal uses a 1157 bulb size. The replacement chart covers vehicle production years spanning 1995 to 2005.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Freightliner FL50 uses the 1156 bulb for the front turn signal across all model years from 1995-2005, and the 1157 bulb for the rear turn signal across the same span of years.
The 1156 is a single-filament bulb operating at 12V and 21W, fitted with a BA15s bayonet base. The single-contact base design means it can only be seated in one orientation.
The 1157 is a dual-filament bulb rated at 12V with filaments drawing 21W and 5W respectively. Its BAY15d bayonet base features offset pins, which physically prevents it from being inserted in place of a 1156 and vice versa.
Both the 1156 and 1157 are ANSI-standardized bulbs recognized across the United States and Canada, meaning they conform to a defined set of electrical and physical specifications rather than being proprietary to any manufacturer.
Because the 1156 and 1157 share a similar appearance but carry different base types, BA15s and BAY15d respectively, the two bulbs are not interchangeable despite their outward resemblance.
The dual-filament configuration of the 1157 used in the rear position allows a single bulb to serve two distinct brightness levels, which is consistent with rear lighting assemblies that combine turn signal and running light functions in one housing.
The front turn signal position on the FL50 uses a single-filament 1156, reflecting a circuit design where only one light intensity level is required at that location.