Toyota Sienna Dome Light Bulb Size

Additional Notes

• The Toyota Sienna dome light draws from three distinct bulb families across its production span: the T10 miniature wedge type (covering bulbs 194, 2825, and 168), and the DE3423 festoon type with end-cap contacts and a 41mm length.
• The T10 wedge form factor is shared by bulbs 194, 2825, and 168, meaning all three occupy the same physical socket style. However, their wattage ratings differ: the 194 draws 3.78W, the 168 draws 4.9W, and the 2825 draws 5W, making them electrically distinct despite their shared housing shape.
• The 2825 carries the designation W2.1x9.5d, which identifies its base pin geometry. This base code is a formal IEC/ANSI designation specifying the pin width and spacing, and it is not shared by the 194 or 168 despite all three being T10 wedge bulbs. Substituting across these three types without confirming base compatibility risks an improper fit.
• The DE3423 festoon bulb, used in the Toyota Sienna for model years 1998-2003, operates on a fundamentally different mounting principle than the wedge types. Festoon bulbs seat by spring tension between two end caps rather than by a wedge base, and the 41mm length is a critical fitment factor since festoon holders are length-specific.
• All four bulb types listed carry ANSI standard designations valid in both the United States and Canada, indicating they conform to a shared North American specification framework rather than region-specific standards.
• The 2023-2024 Sienna uses the 194 bulb, which at 3.78W is the lowest-wattage T10 variant in these specifications. The 2004-2010 Sienna uses the 168 at 4.9W, and the 2011-2018 Sienna uses the 2825 at 5W, the highest wattage among the T10 options listed.
• The festoon DE3423 and the T10 wedge bulbs are not interchangeable under any circumstance, as their socket types, contact methods, and physical forms are entirely different. A festoon holder will not accept a wedge base, and vice versa.
• All bulbs in these specifications operate at 12V, which is consistent with standard automotive electrical systems. This shared voltage does not imply interchangeability, as socket type and wattage remain independent fitment variables.