Ford F-350 Super Duty Map Light Bulb Size

The Ford F-350 Super Duty map light utilizes 906 and 578 bulb sizes depending on the specific production period for the vehicle. Available information covers a range from 1999 through 2016 for the specified lighting components.

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 Size
2011-2016	906
1999-2010	578

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 8W.	906
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V, 12W.	578

Other Locations

Additional Notes

The Ford F-350 Super Duty map light uses two distinct bulb types across its model years, with the 578 festoon bulb fitted in 1999-2010 models and the 906 wedge bulb fitted in 2011-2016 models.
The 906 bulb is a T10 miniature wedge type, meaning it uses a wedge-shaped base that friction-fits directly into a socket without pins or end caps.
The 578 bulb is a festoon type, meaning it is cylindrical in form and makes electrical contact through metal end caps pressed against spring-loaded contacts within a festoon-style holder.
The 578 festoon bulb has a 41mm length, which is a critical fitment specification, as festoon bulbs are sized by length and an incorrect length will not seat properly in the holder.
The 906 and 578 bulbs are not interchangeable, as they use fundamentally different socket types, wedge versus festoon, and cannot be physically substituted for one another without a socket modification.
Both the 906 and 578 bulbs operate at 12 volts, consistent with standard automotive electrical systems.
The 578 bulb is rated at 12 watts, while the 906 is rated at 8 watts, meaning the two bulbs draw different amounts of current even though both run on 12 volts.
Both bulb designations conform to ANSI standards as recognized in the United States and Canada, indicating standardized physical and electrical specifications across manufacturers.