Cadillac Brougham Map Light Bulb Size

The Cadillac Brougham map light requires bulb sizes 561, 912, and 1004 depending on the specific version of the interior lighting component. Available data for the bulb sizes covers the range from 1987 to 1992.

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
1990-1992	561
1989	912
1987-1988	1004

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 44mm length, end-cap contacts. 12V, 12W.	561
ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W.	912
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1004

Other Locations

Additional Notes

The Cadillac Brougham map light specifications span the 1987-1992 model years, covering three distinct bulb types across that range.
The 561 is the most frequently specified bulb in these records, appearing across the 1990-1992 model years. It is a festoon-style bulb measuring 44mm in length with end-cap contacts, rated at 12V and 12W under the ANSI standard.
Festoon bulbs like the 561 make contact at both ends of the housing rather than through a base, which distinguishes their fitment from wedge or bayonet types and makes them non-interchangeable with those formats.
The 1989 Cadillac Brougham map light uses the 912 bulb, a T15 wedge type rated at 12V and 12W. It is noted as a variant of the 921, meaning the two share a close relationship in design, though they are not identical and substitution depends on specific socket tolerances.
The 1987-1988 model years specify the 1004 bulb, which carries a BAY15d bayonet base and a dual-filament design rated at 12V with outputs of 21W and 5W respectively.
The dual-filament construction of the 1004 is a notable characteristic, as it allows two separate brightness levels within a single bulb. This is the same base configuration used by the 1157, of which the 1004 is a recognized variant.
Because the 561, 912, and 1004 each use a different base type, festoon end-cap, wedge, and bayonet respectively, none of the three are physically interchangeable with one another despite sharing the same 12V operating voltage.
All three bulb types in these specifications conform to ANSI standards applicable in both the United States and Canada.