Cadillac Brougham Headlight Bulb Size

The Cadillac Brougham high beam headlight uses a 9004 or H4651 bulb size, while the low beam headlight requires a 9004, H4652, or H4656 bulb size. The replacement chart covers 1987 to 1992 production years with corresponding bulb specifications.

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

High Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1990-1992	9004	HB1	Check Price
1987-1989	H4651	H4651	Check Price

Low Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1990-1992	9004	HB1	Check Price
1989	H4652	H4652	Check Price
1987-1988	H4656	H4656	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament halogen bulb with P29t base. 12V, 65W/45W.	9004	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656	Check Price

Other Locations

Additional Notes

The 9004 bulb is a dual-filament halogen unit operating at 12V with a P29t base, rated at 65W on the high beam filament and 45W on the low beam filament. Its dual-filament design allows a single bulb to serve both high and low beam functions within one housing.
The Cadillac Brougham (1990-1992) uses the 9004 bulb for both high and low beam positions, meaning one bulb type handles both functions in each headlight assembly.
The H4651, H4652, and H4656 are all 4x6-inch rectangular sealed beam units conforming to ANSI standards for the US and Canadian markets. In sealed beam units, the lens, reflector, and filament are fused into a single glass envelope, so the entire unit is replaced rather than an internal bulb.
The 1989 Brougham uses the H4651 for high beam and the H4652 for low beam. Although both are 4x6-inch rectangular sealed beam variants, they are distinct part numbers and are not interchangeable between positions.
The 1987-1988 Brougham uses the H4651 for high beam and the H4656 for low beam. The H4656 and H4652 are separate sealed beam types despite sharing the same physical format, and substituting one for the other across model years is not supported by the specifications.
A transition in headlight technology occurred between the 1989 and 1990 model years, when the Brougham moved from sealed beam units to the replaceable 9004 halogen bulb format.
All bulb types listed across the full 1987-1992 range conform to ANSI standards applicable to the US and Canadian markets, indicating regional standardization rather than global fitment.
The low beam position across the 1987-1989 model years used three different sealed beam part numbers (H4656 for 1987-1988 and H4652 for 1989), while the high beam position used the same H4651 unit throughout that same period.