The Mercedes-Benz 380SL uses a P21/5W bulb size for the front turn signal and a P21W bulb size for the rear turn signal. The replacement chart covers 1981 to 1985 model production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz 380SL uses two distinct bulb types across its turn signal positions: the P21/5W at the front and the P21W at the rear, both conforming to ECE standards recognized in Europe and worldwide.
Both bulb types operate on a 12-volt electrical system, which was the standard automotive voltage for production vehicles of this era.
The front turn signal position across the 1981-1985 model years calls for the P21/5W, a dual-filament bulb rated at 21W and 5W respectively.
The dual-filament design of the P21/5W allows a single bulb to serve two lighting functions simultaneously, with the 21W filament typically handling the turn signal and the 5W filament serving a secondary role such as a parking or position light.
The P21/5W uses a BAY15d bayonet base, which is an offset twin-pin fitting. The asymmetric pin placement of the BAY15d base prevents incorrect installation, as the bulb can only be seated in one orientation.
The rear turn signal position across the 1981-1985 model years calls for the P21W, a single-filament bulb rated at 21W.
The P21W uses a BA15s bayonet base, which is a single-contact fitting with two side pins at the same height. This base type is not interchangeable with the BAY15d base used by the P21/5W.
Although both bulbs share a 21W primary filament rating, the P21/5W and P21W are not interchangeable due to their differing base types and filament configurations.