The Ford L8513 front turn signal uses a 1157 bulb size, while the rear turn signal accommodates either 1157 or 1156 bulb sizes. The replacement chart covers vehicle production years spanning 1996 to 1998.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford L8513 uses two distinct bulb types across its turn signal positions: the 1157 and the 1156, both of which conform to ANSI standards recognized in the United States and Canada.
The 1157 is a dual-filament bulb operating at 12V with a 21W/5W output, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve two brightness levels, commonly used where a turn signal and a running or brake light function share one housing.
The 1156 is a single-filament bulb operating at 12V with a 21W output, mounted on a BA15s bayonet base. It serves only one lighting function per socket.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically distinct and not interchangeable. The BAY15d has offset locating pins to prevent incorrect installation of a single-filament bulb in a dual-filament socket.
The Ford L8513 front turn signal position uses the 1157 bulb across the 1996-1998 model years.
The rear turn signal position of the Ford L8513 uses the 1157 in 1998 but uses the 1156 in 1996-1997, meaning the rear socket specification changed between the 1997 and 1998 model years.
Because the 1157 and 1156 use different base types, a 1156 bulb cannot serve as a direct replacement in any socket specified for the 1157, and vice versa.