The Ford F-800 front and rear turn signal bulbs utilize either 1157 or 1156 bulb sizes depending on production specifications. The replacement chart covers 1980 through 1999 model years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford F-800 turn signal specifications cover model years 1980-1999, with two bulb types appearing across both front and rear positions: the 1157 and the 1156.
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. Its dual-filament design allows it to serve both signaling and running light functions within a single housing.
The 1156 is a single-filament bulb rated at 12V at 21W, mounted on a BA15s bayonet base. It serves only one lighting function per socket, unlike the dual-filament 1157.
Both the 1157 and 1156 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to defined electrical and physical specifications within that standardization framework.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically incompatible with each other. The BAY15d base has offset locating pins to prevent incorrect installation, while the BA15s base has symmetrical pins. These two bulbs are not interchangeable.
The Ford F-800 front turn signal position uses the 1157 exclusively across 1981-1999, with the sole exception of the 1980 model year, which uses the 1156.
The rear turn signal position shows considerably more variation between the 1157 and 1156 across the model year range, with no single bulb type holding consistent across all years.
The 1986 Ford F-800 rear turn signal position is the only year in the specifications that carries two separate entries distinguished by body configuration, with the Cab variant using the 1157 and the Cowl variant using the 1156.