Mercury Tracer front side marker bulbs use 194 or 1157 size, while rear side marker bulbs use 3157, 168, or 194 size specifications. The replacement chart covers 1988 through 1999 production years with corresponding bulb size data.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Tracer draws from four distinct bulb types across its front and rear side marker positions: the 194, 168, 1157, and 3157.
The 194 and 168 are both miniature wedge bulbs sharing the T10 form factor and a 12V operating voltage, though they differ in wattage. The 194 draws 3.78W while the 168 draws 4.9W, making them physically similar but not electrically identical.
Because the 194 and 168 share the T10 wedge base, one may fit the socket of the other, yet the wattage difference means substituting one for the other falls outside the factory specification.
The 1157 is a dual-filament bulb with a BAY15d bayonet base rated at 12V and 21W/5W. Its bayonet mount is mechanically distinct from the wedge-style bases used by the 194, 168, and 3157, so it is not interchangeable with those types.
The 3157 is a dual-filament wedge bulb in the T25 form factor, rated at 12V and 27W/7W. Although it is a wedge type like the 194 and 168, its larger T25 housing is physically incompatible with T10 sockets.
All four bulb types conform to ANSI standards recognized in both the United States and Canada.
For the front side marker on the Mercury Tracer, the 194 is specified for 1997-1999, while the 1992 model year uses the 1157, a bulb with a fundamentally different base type and significantly higher wattage output.
The rear side marker position shows variation across multiple model years. The 3157 is specified for 1998-1999, the 168 covers 1988-1989, 1991, and 1997, and the 194 is listed for 1992.
The 1997 Tracer presents a split fitment: the front side marker uses the 194 while the rear uses the 168. Both are T10 wedge bulbs but with different wattage ratings, so they are not direct substitutes for each other despite their shared base style.
The 1998-1999 rear side marker upgrade to the 3157 represents a shift to a dual-filament T25 wedge bulb, which operates at a notably higher wattage than the single-filament T10 types used in earlier model years.