The Cadillac Brougham front turn signal uses 2057NA or 1157 bulb sizes, while the rear turn signal requires 3057 or 2057 bulb sizes. The replacement chart covers 1987 through 1992 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Cadillac Brougham front turn signal uses the 2057NA bulb for the 1990-1992 model years and the 1157 bulb for the 1987-1989 model years.
The rear turn signal uses the 3057 bulb for the 1990-1992 model years and the 2057 bulb for the 1987-1989 model years.
All four bulb types found in these specifications are dual-filament designs, meaning each bulb serves two brightness levels within a single housing, typically one filament for steady running light use and one for the brighter turn signal flash.
The 1157, 2057, and 2057NA bulbs all share the BAY15d bayonet base, a two-pin offset base that physically locks the bulb into the socket with a twist.
The 3057 is a wedge-style bulb in the T25 form factor, which uses no base pins and is instead held in place by the tension of the socket itself, making it physically incompatible with the BAY15d sockets used by the other three bulb types.
The 2057NA is a natural amber glass variant of the 2057, with the amber tint built into the glass envelope rather than applied through a colored lens or housing.
The 2057 and 2057NA share identical wattage ratings of 26.9W and 8W across their two filaments, and both are described as brighter variants of the 1157, which is rated at 21W and 5W.
Because the 1157, 2057, and 2057NA all use the BAY15d base, a physical fit between these types is possible, but the wattage differences mean they are not electrically equivalent substitutes for one another.
All bulbs listed in these specifications conform to ANSI standards recognized in both the United States and Canada.
All bulbs in these specifications operate at 12 volts, consistent with the standard electrical system voltage of passenger vehicles in this era.