The Ford L9513 front turn signal uses a 1157 bulb size, while the rear turn signal accommodates 1157 and 1156 bulb sizes. The replacement chart covers vehicle production years from 1996 to 1998 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 1157 bulb is a dual-filament type operating at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The BAY15d base features two pins offset at different heights, which physically prevents incorrect installation of single-filament alternatives.
The 1156 bulb is a single-filament type operating at 12V at 21W, mounted on a BA15s bayonet base. The BA15s base features a single pin, making it mechanically incompatible with the dual-filament 1157 socket.
Both the 1157 and 1156 are ANSI-standardized bulbs recognized across the United States and Canada, meaning the specifications conform to a defined performance and dimensional standard rather than a proprietary one.
The Ford L9513 uses the 1157 bulb for the front turn signal across all three model years covered, specifically 1996-1998.
The Ford L9513 rear turn signal uses the 1157 bulb for 1997-1998 but uses the 1156 bulb for the 1996 model year, representing a difference in socket type between those years.
Because the 1996 rear turn signal uses the single-filament 1156 while the 1997-1998 rear turn signal uses the dual-filament 1157, the two bulbs are not interchangeable due to differing base pin configurations and filament counts.
The dual-filament design of the 1157 allows a single bulb to serve two lighting functions simultaneously, which is why it is commonly used in positions where both turn signal and running light functions are combined.