The Freightliner FL80 front turn signal requires a 1156 bulb size while the rear turn signal uses a 1157 bulb size. The replacement chart covers vehicle production spanning 1991 to 2005 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Freightliner FL80 uses the 1156 bulb for the front turn signal across all model years from 1991-2005, and the 1157 bulb for the rear turn signal across that same production span.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. The single-filament design means it serves one lighting function only, which is consistent with its front turn signal application.
The 1157 is a dual-filament bulb rated at 12V with filaments drawing 21W and 5W respectively, fitted with a BAY15d bayonet base. The dual-filament configuration allows it to operate at two brightness levels, supporting both turn signal and running light functions from a single housing.
Although both bulbs share a 12V operating voltage and a bayonet-style base, the 1156 and 1157 are not interchangeable. The BA15s base of the 1156 has a single locating pin, while the BAY15d base of the 1157 has two offset pins, preventing cross-installation between the front and rear positions.
Both the 1156 and 1157 are ANSI-standardized bulbs recognized in the United States and Canada, meaning replacement units sourced from any manufacturer conforming to that standard will share the same electrical and physical specifications.
The consistent use of a single bulb type across all fifteen model years in each position indicates that no mid-cycle changes were made to the turn signal bulb specifications for the FL80 throughout its documented production run.