Mercedes-Benz G550 Headlight Bulb Size

Additional Notes

• The D1S bulb is the most prevalent type across these specifications, appearing in both high beam and low beam positions for the Mercedes-Benz G550 across the 2011-2018 model years.
• The D1S is a high-intensity discharge (HID) bulb standard, operating on a ballast-driven arc discharge system rather than a traditional filament. It produces light by igniting an electric arc between two tungsten electrodes within a quartz capsule filled with xenon gas and metal halide salts.
• The 9003 bulb type is a dual-filament halogen bulb that serves both high and low beam functions within a single housing. It operates on a standard 12-volt automotive electrical system and does not require a ballast.
• For the 2009-2010 G550, the headlamp system installed on the vehicle determines the correct bulb type. Units equipped with halogen capsule headlamps require the 9003, while units equipped with HID headlamps require the D1S.
• Because the 9003 and D1S operate on fundamentally different electrical systems, one cannot be substituted for the other regardless of physical fit. The D1S requires a high-voltage igniter and ballast that halogen-equipped vehicles do not carry.
• The D1S designation includes the suffix "S" to indicate that the bulb is designed for use in projector-style headlamp housings, as opposed to the D1R variant, which is intended for reflector housings. This distinction affects light distribution and is not interchangeable between housing types.
• From 2011 onward, the G550 specifications list only the D1S for both beam positions, indicating that the halogen capsule headlamp option present in 2009-2010 was no longer offered in subsequent model years.
• The single D1S bulb serving both high and low beam functions in a bi-xenon projector system uses a mechanical shield or solenoid within the projector housing to switch between beam patterns, rather than relying on separate filaments as the 9003 does.