Cadillac Seville Headlight Bulb Size

Additional Notes

• The 9005 bulb is the most widely used high beam type across the Cadillac Seville's headlight history, appearing in every model year from 1992-2004. It is a single-filament halogen bulb rated at 12V and 65W, fitted with a P20d base, and conforms to the ANSI standard applicable in the United States and Canada.
• The 9006 bulb serves as the low beam counterpart to the 9005 across the 1992-2004 range, with the exception of years where HID lamps were available. It is a single-filament halogen bulb rated at 12V and 55W, using a P22d base. Although the 9005 and 9006 share a similar wattage class and ANSI origin, their bases differ and the two types are not interchangeable.
• The 9004 is a dual-filament halogen bulb rated at 12V with a split wattage of 65W for high beam and 45W for low beam, using a P29t base. In the Cadillac Seville, it served both the high beam and low beam functions within a single unit for model years 1986-1991, meaning one bulb per housing handled both lighting modes.
• For the 2001-2004 Cadillac Seville, the low beam position accepted either a 9006 halogen bulb or a D1S HID bulb depending on the headlamp system fitted to the vehicle. These two types are not interchangeable, as the D1S operates at 85V and 35W using a PK32d-2 base with an integral ignitor, and requires a projector-type housing designed specifically for high-intensity discharge operation.
• The D1S bulb conforms to the ECE standard used in Europe and worldwide, rather than the ANSI standard that governs the other bulb types listed in these specifications. Its operating voltage of 85V stands in significant contrast to the 12V rating of all halogen types present in the same fitment data.
• Model years 1976-1985 used sealed beam headlight units rather than replaceable bulbs. The H4651, H4652, and H4656 types are all 4x6-inch rectangular sealed beam units conforming to ANSI standards, in which the lens, reflector, and filament form a single assembly. When the filament fails, the entire unit is replaced rather than an individual bulb.
• The H4651 was used exclusively for the high beam position across all Seville model years from 1976-1985, while the low beam position across the same era alternated between H4652 and H4656 depending on the specific year. H4652 and H4656 are both variants of the 4x6-inch rectangular sealed beam format and share the same physical form factor as H4651, though they are distinct part numbers and are not confirmed as interchangeable by these specifications.
• The low beam specifications for 1983 and 1985 call for the H4656, while 1984 calls for the H4652, indicating that consecutive model years within the sealed beam era did not always share the same low beam unit. The same alternating pattern is present in earlier years, with H4652 specified for 1976, 1979-1981, and H4656 for 1977-1978 and 1982-1983.