Chevrolet Chevette Brake Bulb Size

Additional Notes

• The Chevrolet Chevette uses two different brake bulb sizes across its production run, with the 1157 fitted from 1976-1982 and the 2057 fitted from 1983-1987.
• Both the 1157 and 2057 are ANSI-standardized dual-filament bulbs sharing the same BAY15d bayonet base, meaning the physical base type did not change between the two specification periods.
• The BAY15d base is a double-contact bayonet fitting with offset pins, a design that prevents incorrect single-filament bulbs from being seated in a dual-filament socket.
• The dual-filament construction in both bulb types serves the brake light circuit by allowing one filament to function as a running light and the other as a brighter stop light signal.
• The 2057 operates at 26.9W on its high filament, compared to the 1157's 21W, making the 2057 the higher-output bulb of the two despite sharing the same base and voltage rating of 12V.
• The low filaments differ as well, with the 2057 rated at 8W and the 1157 at 5W, both running on 12V.
• Although the BAY15d base is physically identical between the 1157 and 2057, substituting one for the other results in different wattage output, which affects brightness levels in the brake circuit.
• The Chevrolet Chevette's brake bulb specification changed from the 1157 to the 2057 between the 1982 and 1983 model years, representing a shift to a higher-wattage bulb for the stop and tail functions.