Volvo 1800 front turn signal bulbs measure 1157 in size, while rear turn signal bulbs measure 1156 in size. The replacement chart covers vehicle production spanning 1969 to 1973.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Volvo 1800 uses two distinct bulb types across its front and rear turn signal positions for the 1969-1973 model years.
The front turn signal on the Volvo 1800 takes a 1157 bulb across all five model years covered in the specifications.
The 1157 is a dual-filament bulb operating at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base features two offset pins, which physically prevents it from being seated in a single-filament socket, making cross-position substitution impossible without modification.
The rear turn signal position calls for a 1156 bulb across the same 1969-1973 span.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base that uses two symmetrically placed pins.
Although the 1156 and 1157 share the same physical envelope size and both operate on a 12V system, their bases are not interchangeable due to the differing pin configurations of BA15s and BAY15d.
Both the 1156 and 1157 are ANSI-standardized bulbs recognized in the United States and Canada, meaning replacements conforming to those designations are widely available across those markets.