Mercedes-Benz SL320 Headlight Bulb Size

Additional Notes

• The 9004 bulb is the most frequently specified type across the Mercedes-Benz SL320 headlight data, covering both high beam and low beam positions for the 1994-1997 model years under halogen capsule headlamp configurations. It is a dual-filament halogen bulb built to the ANSI standard used in the US and Canada, operating at 12V with a 65W filament for high beam and a 45W filament for low beam, fitted with a P29t base.
• The dual-filament design of the 9004 means a single bulb serves both the high beam and low beam functions within one housing, which is reflected in the SL320 specifications listing the same 9004 size for both sub-parts when halogen capsule headlamps are present.
• The H1 bulb is specified for the high beam position on the Mercedes-Benz SL320 in 1995-1997 when HID or xenon headlamps are fitted. Unlike the 9004, the H1 is a single-filament bulb, meaning it handles only one lighting function. It uses a P14.5s base and operates at 12V, 55W under the ECE standard, though it also carries approval in the US and Japan.
• The D2S bulb is specified for the low beam position in 1996-1997 models equipped with HID headlamps. It is a high-intensity discharge xenon bulb rated at 85V and 35W, using a P32d-2 base. The D2S type is designed specifically for projector-type housings and requires an external ignitor to initiate the arc discharge, making it electrically and mechanically incompatible with standard halogen sockets.
• On SL320 units fitted with HID headlamps in 1996-1997, the high beam and low beam positions use different bulb types from separate standards: the H1 (ECE, halogen) for high beam and the D2S (ECE, HID) for low beam. These two bulbs are not interchangeable due to differences in base type, operating voltage, and housing requirements.
• The 9004 and H1 bulbs are not interchangeable despite both being 12V halogen types. The 9004 uses a P29t base and a dual-filament construction, while the H1 uses a P14.5s base with a single filament. Substituting one for the other is not possible without modifying the socket or housing.
• The 1994 SL320 is specified with the 9004 bulb only, with no HID or xenon variant listed for that year. This contrasts with 1995-1997, where alternative bulb types are listed alongside the 9004 depending on headlamp system.
• The D2S bulb's 85V operating voltage is substantially higher than the 12V supply voltage of the vehicle's electrical system. The required external ignitor steps up the voltage to strike the initial arc, after which the ballast regulates power to sustain the discharge at the rated 35W output.