Land Rover Defender 90 brake bulbs utilize P21/5W size for standard brake applications and P21W size for the center high mount stop light. The replacement chart covers vehicle production years spanning 1994 to 1997 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Land Rover Defender 90 uses two distinct ECE-standard bulb types across its brake lighting system: the P21/5W for the main brake lights and the P21W for the center high mount stop light.
Both bulb types follow ECE regulations, a lighting standard adopted across Europe and much of the world, and both operate on a 12V electrical system.
The P21/5W is a dual-filament bulb, meaning it serves two functions within a single unit. Rated at 21W and 5W respectively, the higher-wattage filament activates for braking while the lower-wattage filament typically handles a secondary function such as a tail light.
The P21/5W uses a BAY15d bayonet base. The BAY15d designation indicates an offset dual-contact base, a design that physically prevents incorrect filament orientation during installation.
The P21W is a single-filament bulb rated at 21W and uses a BA15s bayonet base. The BA15s base is a single-contact design, distinct from the dual-contact BAY15d used by the P21/5W.
Because the P21W and P21/5W share a similar physical profile but have different base types, BA15s and BAY15d are not interchangeable. Substituting one for the other is not possible without a compatible socket.
The P21/5W specification for the main brake lights on the Defender 90 applies consistently across the 1994-1997 model years covered in the data.
The P21W specification for the center high mount stop light similarly remains unchanged across the 1994-1997 model years covered in the data.