Land Rover Discovery brake bulb sizes include P21/5W and P21W configurations, with the center high mount stop light bulb utilizing a P21W size. The replacement chart covers vehicle production spanning 1994 to 2004.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The two bulb types specified across the Land Rover Discovery brake lighting system are the P21/5W and the P21W, both of which conform to ECE standards used in Europe and worldwide.
The P21/5W 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 offset pins of the BAY15d base are positioned at different heights to ensure correct polarity orientation during installation.
The P21W is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base. The BA15s base features two pins at the same height, distinguishing it physically from the BAY15d base used by the P21/5W.
Because the BAY15d and BA15s bases are physically different, the P21/5W and P21W are not interchangeable, even though both share the same 21W primary wattage rating.
For the Land Rover Discovery, the brake light specification alternates between P21/5W and P21W across model years from 1994 to 2004, meaning the correct bulb type is year-dependent for that position.
The P21/5W is specified for the brake light position in the 1994-1998, 2000, and 2003-2004 model years of the Discovery.
The P21W is specified for the brake light position in the 1999, 2001, and 2002 model years of the Discovery.
The Center High Mount Stop Light on the Land Rover Discovery uses the P21W across all listed model years from 1994 to 2004, making it consistent regardless of the year-to-year variation seen in the main brake light position.
A vehicle in a given model year may therefore require two different bulb types across its brake lighting positions, as the main brake light and the Center High Mount Stop Light do not always share the same specification.
In the 2003-2004 model years, the main brake light calls for a P21/5W while the Center High Mount Stop Light calls for a P21W, confirming that both bulb types are present simultaneously on the same vehicle.