Ford Fairmont front turn signal bulbs utilize 1157 or 1157NA size, while rear turn signal bulbs use 1157 size. The replacement chart covers 1978 to 1983 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 1157 is the dominant bulb type across these specifications, appearing in both the front and rear turn signal positions for the Ford Fairmont across the 1980-1983 model years, as well as the rear turn signal position for 1978-1979.
The 1157 is a dual-filament bulb, meaning it serves two brightness levels within a single housing. The higher 21W filament handles the active turn signal flash, while the lower 5W filament serves as a standing marker or parking light.
Both the 1157 and 1157NA operate on a 12V electrical system and share the BAY15d bayonet base, which is a double-contact base with two offset pins that prevent incorrect insertion.
The 1157NA differs from the standard 1157 solely in its natural amber glass envelope. This tinting produces an amber output without relying on an amber lens, and it was specified for the front turn signal positions on the 1978-1979 Ford Fairmont.
Because the 1157 and 1157NA share identical base types, voltage ratings, and wattage ratings, they are physically interchangeable. However, substituting a clear 1157 for an 1157NA in a position that depends on the bulb itself for amber color output would alter the visible light color.
The front turn signal specification shifts from the 1157NA to the standard 1157 between the 1979 and 1980 model years, indicating a change in how the amber color requirement was met, likely through lens color rather than bulb glass from 1980 onward.
The rear turn signal position uses the clear 1157 for all six model years covered, from 1978 through 1983, with no variation across that span.