Ford Sunliner Back Up Light Bulb Size

Additional Notes

• The Ford Sunliner back up light specifications span model years 1953 through 1960, covering four distinct bulb types across that range.
• The 1141 and 1156 bulbs share identical electrical ratings of 12V and 21W, and both use a BA15s single-contact bayonet base, making them functionally similar despite carrying different ANSI part numbers. The Ford Sunliner used the 1156 only in 1958, while the 1141 covered 1956-1957 and 1959.
• The 1073 bulb, fitted to the 1960 Ford Sunliner, is a lower-wattage variant of the 1156, rated at 12V and 13W rather than 21W. Although it shares the same BA15s bayonet base, its reduced wattage means it is not a direct equivalent replacement for the 1156 or 1141.
• The 1129 bulb, used across the 1953-1955 model years, is a dual-filament bulb with a BAY15d bayonet base, rated at 12V and 21/5W. Its base type differs from the BA15s found on the 1073, 1141, and 1156 bulbs, making cross-substitution between these groups physically incompatible.
• The BAY15d base on the 1129 features two offset pins, whereas the BA15s base on the single-filament bulbs carries a single contact pin. These two base types are not interchangeable.
• The 1129 is noted as a variant of the 1157, which is a widely referenced dual-filament bulb. The two filaments in the 1129 operate at different wattages, 21W and 5W, serving separate circuit functions within the same housing.
• All four bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada, indicating standardized physical and electrical tolerances across the range.
• The back up light circuit on the 1953-1955 Ford Sunliner relied on a dual-filament bulb, while all subsequent model years through 1960 used single-filament bulbs, reflecting a change in bulb architecture at the 1956 model year.