Ford C600 front and rear turn signal bulbs utilize 1156 and 1157 sizes, with the front position accommodating either bulb size and the rear position similarly accepting both options. The replacement chart covers 1980 through 1986 production years with corresponding bulb size specifications for each model year.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Ford C600 turn signal specifications cover model years 1980-1986, with front and rear positions each drawing from two bulb types: the 1156 and the 1157.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and recognized under the ANSI standard in both the United States and Canada.
The 1157 is a dual-filament bulb rated at 12V with filaments drawing 21W and 5W respectively, fitted with a BAY15d bayonet base, and likewise recognized under the ANSI standard in both the United States and Canada.
Although the 1156 and 1157 share a 12V operating voltage and a bayonet-style base, their bases are not interchangeable. The BA15s base of the 1156 has a single contact pin, while the BAY15d base of the 1157 has two offset contact pins, making physical substitution between the two types impossible without modification.
The Ford C600 front turn signal uses the 1156 for most of the covered period, specifically 1980 and 1982-1986, with the exception of 1981 and 1983, which specify the dual-filament 1157.
The rear turn signal of the Ford C600 uses the 1157 consistently across 1981-1986, while the 1980 model year specifies the single-filament 1156 for that position.
The dual-filament nature of the 1157 allows it to serve two lighting functions within a single housing, with the higher-wattage filament typically handling the turn signal function and the lower-wattage filament serving a secondary role such as a running or parking light.
The 1156, having only one filament, is limited to a single lighting function per socket, which is consistent with its use in dedicated turn signal positions where no secondary lighting function is required.
For the Ford C600, the front and rear turn signal positions do not share a uniform bulb type across all years, meaning the correct bulb for one position and year is not necessarily correct for the other position or a different year.