Blue Bird Vision School Bus front and rear turn signal bulbs utilize 1157 and 1156 size specifications. The replacement chart documents bulb size data spanning 2010 to 2017 production years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Blue Bird Vision School Bus uses two distinct bulb types across its turn signal positions: the 1157 and the 1156, both of which are ANSI-standardized bulbs recognized in the United States and Canada.
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. The dual-filament design allows a single bulb to serve two lighting functions simultaneously, such as turn signaling and running light operation.
The 1156 is a single-filament bulb rated at 12V at 21W, mounted on a BA15s bayonet base. Its single-filament construction means it serves only one lighting function.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically distinct. The BAY15d base has two offset locating pins to prevent incorrect single-function bulb insertion, while the BA15s base has a single pin. These two bulb types are not interchangeable.
For the 2017 Blue Bird Vision School Bus, both the front and rear turn signal positions specify the 1157 bulb.
For the 2010 model, both the front and rear turn signal positions specify the 1156 bulb, reflecting a different electrical configuration from the 2017 model year.
Because the 1157 and 1156 share the same 21W main filament wattage and a similar bayonet-style base profile, there is a risk of attempted substitution. However, the differing pin configurations make direct substitution physically incompatible without modification.