Peterbilt 348 Map Light Bulb Size

The Peterbilt 348 map light requires a 912 bulb size for proper installation and function within the interior lighting system. Data provided for the specific component covers the range from 2010 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 Size
2010-2017	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 912 bulb is the sole map light bulb size listed for the Peterbilt 348 across the 2010-2017 model years.
The 912 is an ANSI-standardized bulb type, meaning its physical and electrical specifications conform to a recognized North American standard used in both the United States and Canada.
The 912 uses a wedge base, designated T15, which refers to a tubular bulb body approximately 15 eighths of an inch wide that is held in its socket by the tension of the base contacts rather than by a bayonet or screw mechanism.
The 912 operates at 12 volts and consumes 12 watts, which is consistent with standard automotive low-voltage electrical systems.
The 912 is a variant of the 921 bulb. These two types share the same T15 wedge form factor, but they differ in wattage: the 921 is rated at 18 watts, making the two types electrically non-equivalent despite their physical similarity.
Because the 912 and 921 share the same wedge base, the 921 can physically fit the Peterbilt 348 map light socket, but its higher wattage draw may exceed the design tolerance of that circuit.