The Ford Aspire brake light requires a 1157 bulb size for proper installation and function within the lighting assembly. Data for the specific component covers the range from 1994 to 1997.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford Aspire uses the 1157 bulb for brake lighting across all four model years in the specification, covering 1994-1997.
The 1157 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 21W/5W output. The higher wattage filament serves the brake function, while the lower wattage filament serves a secondary function such as running or tail lighting.
The BAY15d bayonet base features two offset pins, a design that prevents incorrect single-filament bulbs from being seated in its place. Substituting a single-filament bulb in a dual-filament socket results in loss of one lighting function.
The center high mount stop light on the Ford Aspire uses the 921 bulb for all four model years covered, 1994-1997.
The 921 is a single-filament wedge-type bulb in the T15 form factor, rated at 12V and 16W. Wedge bulbs rely on their base contacts rather than a separate locking mechanism, making them physically distinct from the bayonet-style 1157.
Both the 1157 and 921 conform to ANSI standards applicable in the United States and Canada, meaning their electrical and physical specifications are standardized across manufacturers within those markets.
The 1157 and 921 are not interchangeable. They differ in base type, filament count, wattage, and physical form factor, and each is assigned to a distinct lighting position on the vehicle.