The Subaru XT brake light requires a 1157 bulb size for proper installation and function within the rear lighting assembly. Data for the specific component covers the period from 1985 through 1991.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Subaru XT uses the 1157 bulb for its brake lights across the full 1985-1991 model range.
The 1157 is a dual-filament bulb operating at 12V with a 21W/5W output, fitted with a BAY15d bayonet base, and standardized under ANSI specifications for the US and Canadian markets.
The dual-filament design of the 1157 allows it to serve two lighting functions within a single housing, which is why it is suited to brake light positions that also handle a secondary function such as running lights.
The Center High Mount Stop Light on the Subaru XT takes the 1156 bulb across the same 1985-1991 model range.
The 1156 is a single-filament bulb operating at 12V with a 21W output, fitted with a BA15s bayonet base, and also standardized under ANSI specifications for the US and Canadian markets.
Although the 1157 and 1156 share a similar physical bayonet base style, the BAY15d base of the 1157 and the BA15s base of the 1156 are not interchangeable, as the pin configurations differ between the two.
The single-filament 1156 in the Center High Mount Stop Light position reflects that this lamp serves a dedicated stop light function only, requiring no secondary filament for an additional lighting mode.