Chevrolet Celebrity Back Up Light Bulb Size

Additional Notes

• The Chevrolet Celebrity back up light specifications span model years 1982 through 1990, with three distinct bulb types appearing across that range: the 1156, 2057, and 1157.
• The 1156 is the most frequently specified bulb across Celebrity model years, appearing in 1984-1985, 1987, and 1990. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W.
• The 2057 appears in 1983, 1986, and 1988. It is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with filament outputs of 26.9W and 8W, making it the highest-wattage bulb in these specifications.
• The 1157 is specified only for the 1982 Celebrity. Like the 2057, it uses a dual-filament design with a BAY15d bayonet base, but it is rated at a lower 12V, 21W/5W output.
• Although the 2057 and 1157 share the same BAY15d bayonet base type, their wattage ratings differ considerably. The 2057 draws 26.9W on its primary filament versus the 1157's 21W, which means the two are not electrically equivalent despite their physical base compatibility.
• The 1156 uses a BA15s single-contact bayonet base, while both the 2057 and 1157 use a BAY15d dual-contact bayonet base. These base types are physically distinct and are not interchangeable with one another.
• All three bulb types conform to ANSI standards applicable in both the United States and Canada, indicating standardized performance and dimensional specifications across those markets.
• The back up light circuit requires only a single active filament for its function. The use of dual-filament bulbs such as the 2057 and 1157 in certain Celebrity model years reflects a shared housing design where the same socket serves multiple lighting functions on the vehicle.