Jaguar XJS Map Light Bulb Size

The Jaguar XJS map light requires bulb size 12961 or 3893 depending on the specific application. Data for the bulb sizes covers the range from 1984 to 1996.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1995-1996	12961
1984-1989	3893

Bulb Specifications

Description	Bulb Size
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base, specialty application. 12V.	3893

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Additional Notes

The Jaguar XJS map light specifications reference two distinct bulb types across the model years covered: the 12961 and the 3893.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, fitted with a W2.1x9.5d base and rated at 12V, 5W. The T10 wedge base is among the most widely used bulb formats in automotive interior lighting.
The 3893 follows the ANSI standard recognized in the United States and Canada. It is a dual-filament bulb with a BAY15d bayonet base, rated at 12V, and classified as a specialty application type. The BAY15d base features offset pins to prevent incorrect installation of a dual-filament bulb in the wrong orientation.
The Jaguar XJS uses the 3893 for map light fitment across the 1984-1989 model years.
The 1995-1996 model years specify the 12961 for the same map light position, representing a different base type and construction from the 3893 used in earlier years.
Because the 12961 uses a wedge base and the 3893 uses a BAY15d bayonet base, the two bulbs are not interchangeable. The socket design for each base type is physically distinct.
The dual-filament construction of the 3893 means it contains two separate filaments within a single envelope, a characteristic that distinguishes it from the single-filament 12961.
The 12961 is rated at 5W, while the 3893 specification provided does not include a wattage value. The two bulbs therefore cannot be assumed to share equivalent light output or power draw.