The Ford L9000 front and rear turn signal bulbs utilize 1157 and 1156 sizes, with specifications varying by application location. The replacement chart covers 1981 through 1997 production years and details bulb size specifications for each signal position.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford L9000 front and rear turn signal positions draw from two bulb types across the full model range: the 1156 and the 1157. Both are ANSI-standardized bulbs used in the United States and Canada, operating at 12 volts with a 21-watt primary filament rating.
The 1157 is a dual-filament bulb rated at 21W/5W and fitted with a BAY15d bayonet base. The dual-filament design allows it to serve both a high-intensity function and a lower-intensity standby or running-light function within a single housing.
The 1156 is a single-filament bulb rated at 21W and fitted with a BA15s bayonet base. Because it carries only one filament, it performs a single switching function rather than the combined role of the 1157.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically distinct. The BAY15d has offset locking pins to prevent incorrect installation, while the BA15s has symmetrical pins. These two bulbs are not interchangeable despite their similar appearance and shared 15mm base width.
On the Ford L9000, the 1990 front turn signal position is headlamp-configuration-dependent. Vehicles with 2 round headlamps take a 1156, while vehicles with 4 rectangular headlamps take a 1157. Selecting the wrong bulb type for the installed headlamp configuration would result in a fitment or circuit mismatch.
A parallel condition exists at the rear turn signal position for the 1991 model year. The 2-round-headlamp configuration calls for a 1156, and the 4-rectangular-headlamp configuration calls for a 1157, indicating that headlamp style influenced the broader lighting circuit design in those production variants.
The front turn signal specification for the 1993-1995 model years calls for the 1156, while the rear turn signal specification for those same years is split, with 1993 using a 1156 and 1994-1995 using a 1157. Front and rear positions therefore do not always share the same bulb type within a given model year.
The 1996-1997 front turn signal position specifies the 1157, whereas the rear turn signal for those same years specifies the 1156. This front-to-rear inversion of bulb types is a recurring pattern across multiple years in the L9000 specifications and reinforces that the two positions must be treated independently when sourcing replacements.