Cadillac DTS high beam and low beam headlight bulbs both utilize the D1S size. The replacement chart covers 2006 through 2011 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Cadillac DTS uses the D1S bulb type for both high beam and low beam headlights across all model years from 2006-2011.
The D1S is a High-Intensity Discharge (HID) xenon bulb, operating at 85 volts and 35 watts, which places it in a different electrical category than conventional halogen bulbs.
A defining characteristic of the D1S is its integrated ignitor, meaning the ignitor is built directly into the bulb unit rather than housed separately in the ballast assembly.
The D1S uses a PK32d-2 base, which is a keyed connector designed to prevent incorrect installation and is not interchangeable with other HID base types such as PK32d-3, used by the D2S.
The D1S is rated under ECE regulations, a standard recognized across Europe and numerous other markets worldwide, governing output, color temperature, and safety requirements for road use.
Because the D1S incorporates an integral ignitor, it is not interchangeable with the D2S bulb, even though both share the same 85V/35W electrical rating and projector-housing application.
The Cadillac DTS shares a single D1S specification for both high and low beam functions, indicating the headlight system relies on projector-type housings that direct the same bulb output for each function.