Fiat 124 front and rear turn signal bulbs utilize 1156 and 1073 sizes, with the front position requiring the 1156 bulb size exclusively. The replacement chart covers 1976 to 1983 model 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 1156 bulb is the dominant fitment across the Fiat 124 turn signal specifications, appearing in both the front and rear positions for the majority of model years covered.
Both the 1156 and 1073 are ANSI-standardized bulbs for the US and Canadian markets, each operating on a 12-volt system with a single filament and a BA15s bayonet base.
The BA15s bayonet base is a single-contact design, which corresponds to the single-filament construction of both bulb types listed in these specifications.
The 1156 operates at 21 watts, while the 1073 operates at 13 watts, meaning the two bulbs draw meaningfully different amounts of current despite sharing the same base type.
Because the 1073 and 1156 share a BA15s bayonet base, one will physically seat in the socket of the other, but the wattage difference makes them non-interchangeable without affecting circuit behavior.
In the Fiat 124, the 1073 appears exclusively in the 1981 rear turn signal position, while all other rear turn signal years in the specifications use the 1156.
The front turn signal position on the Fiat 124 uses the 1156 uniformly across all listed years, 1976-1983.
A lower-wattage bulb such as the 1073 installed in a circuit calibrated for the 1156 may cause a turn signal flasher relay to operate at an incorrect flash rate, since many thermal and electronic flashers are load-dependent.