Porsche 930 front turn signal bulbs measure 1157 in size, while rear turn signal bulbs measure 1156, with each bulb type serving distinct lighting functions on the vehicle. The replacement chart covers 1978 to 1979 production years and documents bulb size specifications for turn signal applications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Porsche 930 (1978-1979) uses two distinct bulb types across its turn signal positions: the 1157 at the front and the 1156 at the rear.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The dual-filament design of the 1157 allows a single bulb to serve two lighting functions simultaneously, which is why it is suited to front turn signal positions where combined signaling and parking light duties are common.
The 1156 is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically distinct and not interchangeable, as the offset pins on the BAY15d base differ from the single-pin alignment of the BA15s base.
Both the 1157 and 1156 are ANSI-standardized types applicable to the US and Canadian markets.
The front and rear turn signal positions on the Porsche 930 require different bulb types, and substituting one for the other would result in an incorrect fitment due to the differing base configurations and filament counts.