Mercury Topaz front and rear turn signal bulbs utilize 2357NA, 2357, 1157, and 3157 bulb sizes depending on location and model variation. The replacement chart covers 1984 to 1994 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 Mercury Topaz front turn signal uses three distinct bulb types across its production run: the 1157, 2357, and 2357NA, all of which share the BAY15d bayonet base and dual-filament construction.
The 2357NA is the most frequently specified bulb across the front turn signal positions, appearing in model years 1985-1987 and 1992-1994.
The 2357NA differs from the standard 2357 in one key respect: its glass envelope is tinted natural amber, which produces the amber signal color without relying on a colored lens.
The 2357 and 2357NA share identical electrical ratings of 12V and 26.9W/8W, with the higher wattage filament serving the turn signal function and the lower wattage filament serving a secondary role such as parking or running light.
The 1157 operates at 12V with a 21W/5W rating, making its high-intensity filament notably less powerful than that of the 2357 and 2357NA at 26.9W.
Despite the wattage difference, the 1157 and 2357 are physically compatible at the socket level, as both use the BAY15d bayonet base, though substituting one for the other results in a difference in output brightness.
The rear turn signal on the Mercury Topaz uses the 3157 for the 1994 model year, which is a wedge-type bulb and is not socket-compatible with the BAY15d bayonet base used by all other bulbs in these specifications.
The 3157 is rated at 12V, 27W/7W, placing its high-intensity filament output close to that of the 2357 and 2357NA, though its physical base type is entirely different.
Front and rear turn signal positions on the 1984-1985 Mercury Topaz both use the 1157, indicating a uniform bulb specification across both positions in those years.
The rear turn signal specifications for model years 1989-1993 are not present in the provided data, while the 1994 rear position shifts to the 3157, which represents a change in base type from the BAY15d bayonet used in the 1986-1988 rear positions.