Freightliner Cascadia Stepwell Bulb Size

The Freightliner Cascadia stepwell light requires a 12961 bulb size for proper illumination of the vehicle entrance area. Provided information covers the specific time period from 2008 through 2017.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Type	Shop
2008-2017	12961	Check Price

Bulb Specifications

Description	Type	Shop
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12961	Check Price

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Additional Notes

The Freightliner Cascadia stepwell position uses the 12961 bulb across all listed model years from 2008-2017, with no variation in fitment throughout that period.
The 12961 is a Philips part number designating a miniature wedge bulb in the T10 form factor, which refers to a tubular bulb body approximately 10 millimeters wide.
The bulb operates on a 12-volt electrical system and draws 5 watts, placing it in the low-wattage range typical of interior and courtesy lighting applications.
The W2.1x9.5d base type is a wedge-style base, meaning the bulb is held in its socket by the tension of the base itself rather than by a bayonet or screw mechanism.
T10 wedge bulbs with the W2.1x9.5d base are a widely standardized format, and the 12961 is interchangeable with other T10 wedge bulbs sharing the same voltage, wattage, and base specification.
Because the stepwell bulb serves a functional safety role in illuminating entry and exit points, substitutions with bulbs of differing wattage or base type risk improper fit or inadequate light output.