GMC Yukon Back Up Light Bulb Size

The GMC Yukon back up light uses bulb sizes 921, 7441, 2456, and 3156 depending on the specific vehicle configuration. Available data for the bulb sizes covers the range from 1992 to 2023.

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

Back Up Light

Years	Bulb Size
2023	921
2015-2019	921
2014	7441
1999	2456
1997-1998	3156
1995-1996	2456
1994	3156
1992-1993	2456

Outer Back Up Light

Years	Bulb Size
2017-2020	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament wedge bulb (T20), amber. 12V, 21W.	7441
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156

Other Locations

Additional Notes

The 921 bulb is the most frequently specified size across the GMC Yukon back up light data, covering the 2015-2019 and 2023 model years for the standard back up light position, as well as the 2017-2020 model years for the outer back up light position.
The 921 is a T15 wedge bulb rated at 12 volts and 16 watts, conforming to ANSI standards recognized in both the United States and Canada.
The 2014 GMC Yukon back up light uses the 7441 bulb, which differs from the 921 used in surrounding model years. The 7441 is a T20 single-filament wedge bulb rated at 12 volts and 21 watts, and it is amber in color rather than clear.
Because the 7441 is amber and the 921 is not, these two bulbs are not interchangeable despite both being wedge-type designs operating at 12 volts.
The 3156 bulb is specified for the 1994, 1997, and 1998 model years. It is a T25 single-filament wedge bulb rated at 12 volts and 27 watts, making it the highest-wattage bulb among those listed in these specifications.
The 2456 bulb is specified for the 1992, 1993, 1995, 1996, and 1999 model years. Unlike the wedge-type bulbs in these specifications, the 2456 is a festoon bulb intended for specialty applications, rated at 12 volts.
The festoon form factor of the 2456 means it is physically incompatible with the wedge sockets used by the 921, 7441, and 3156 bulbs, and substitution between these types is not supported by the specifications.
The T15, T20, and T25 designations on the wedge bulbs refer to the width of the bulb body, with T25 being the widest. This size difference affects socket fitment, and these wedge bulbs are not interchangeable with one another despite sharing the same 12-volt operating voltage.
All four bulb types listed in these specifications conform to ANSI standards applicable in both the United States and Canada.
The outer back up light position on the GMC Yukon, covering 2017-2020, exclusively uses the 921 bulb across all listed years for that sub-position.