Peterbilt 388 Map Light Bulb Size

The Peterbilt 388 map light utilizes a 912 bulb size for the interior lighting component. Data for the specific bulb requirements covers the range from 2011 to 2015.

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
2011-2015	912

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W.	912

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Additional Notes

The Peterbilt 388 uses the 912 bulb size for the map light across the 2011-2015 model years.
The 912 is an ANSI-standardized bulb, meaning it conforms to a defined set of electrical and physical specifications recognized across the United States and Canada.
It belongs to the T15 wedge bulb family, a designation that refers to its tubular glass envelope and wedge-style base, which connects directly into a socket without a separate metal base or pins.
The 912 operates at 12 volts and 12 watts, which places it in the low-wattage range typical of interior cabin lighting applications such as map lights.
The 912 is noted as a variant of the 921 bulb. While both share the T15 wedge form factor and 12-volt rating, the 921 draws 18.4 watts, making the two bulbs electrically distinct and not directly interchangeable without consideration of the wattage difference.