The Mercury Grand Marquis brake light utilizes 1157, 2458, 3157, and 4157 bulb sizes depending on the specific production period. Available information covers the span from 1975 through 2011.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Grand Marquis brake light specifications cover model years 1975 through 2011, with three distinct bulb types used across that span: the 1157, 3157, and 4157.
The 3157 is the most frequently specified brake bulb in these records, covering the Mercury Grand Marquis from 1987 through 2005, a span of nineteen model years.
Both the 3157 and 4157 are dual-filament wedge bulbs of the T25 type, operating at 12V with a 27W high-filament and 7W low-filament rating under the ANSI standard applicable in the US and Canada.
Although the 3157 and 4157 share identical voltage and wattage ratings and the same T25 wedge form, they are distinct part numbers and are not confirmed as interchangeable by these specifications.
The Mercury Grand Marquis shifted from the 3157 to the 4157 between the 2005 and 2006 model years, affecting the brake light position.
The 1157, used on the Grand Marquis from 1975 through 1986, uses a BAY15d bayonet base rather than a wedge base, making it physically incompatible with the sockets designed for the 3157 or 4157.
The 1157 operates at 12V with a 21W high-filament and 5W low-filament rating, which is lower than the 27W/7W output of the 3157 and 4157 used in later model years.
The 912 wedge bulb, a single-filament T15 type rated at 12V and 12W, is specified for the Center High Mount Stop Light on the Grand Marquis across all model years from 1986 through 2011.
The 912 is noted as a variant of the 921 bulb. These two types share the same T15 wedge base but differ in wattage, which is a relevant fitment consideration.
The Center High Mount Stop Light on the Grand Marquis uses a single-filament bulb, while the primary brake light position uses dual-filament bulbs throughout all model years covered in these specifications.