Mack Pinnacle Back Up Light Bulb Size

The Mack Pinnacle back up light bulb uses a 1156 size bulb for this vehicle model. The replacement chart covers vehicle production years from 2011 to 2017 with corresponding bulb size specifications.

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
2011-2017	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

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Additional Notes

The 1156 is the specified back up light bulb size for the Mack Pinnacle across all listed model years from 2011-2017.
The 1156 bulb follows the ANSI standard, which is the recognized specification body for automotive lighting in the United States and Canada.
This bulb type uses a BA15s bayonet base, a single-contact fitting where the "15" refers to the 15mm base width and the "s" denotes a single contact point at the base.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which aligns with its application as a dedicated back up light.
The bulb operates at 12 volts, consistent with the standard electrical system voltage found in commercial vehicles.
At 21 watts, the 1156 produces a relatively high output for an incandescent automotive bulb, which is typical for a back up light requiring strong rearward illumination.
The BA15s bayonet base is not interchangeable with the BA15d base, which carries two contact points. Substituting a dual-contact bulb in a single-contact socket would result in an improper fit.