The GMC Yukon XL back up light requires a bulb size of 921 for the specific lighting component located at the rear of the vehicle. Available data for the specified bulb covers the range from 2015 to 2023.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 921 bulb is the sole bulb type specified across all listed back up light positions for the GMC Yukon XL.
The 921 follows the ANSI standard, meaning it conforms to a standardized specification recognized in both the United States and Canada.
It uses a wedge-style base, classified under the T15 form factor. A wedge base requires no separate metal connector, as the glass envelope itself forms the electrical contact when inserted into the socket.
The 921 operates at 12 volts and draws 16 watts, which is consistent with standard automotive electrical systems.
For the general back up light position, the 921 bulb applies to the GMC Yukon XL for model years 2015-2019 and 2023.
For the Outer Back Up Light position, the 921 bulb applies to model years 2017-2020.
The 921 shares its T15 wedge base with several other bulb types in the same family, such as the 912 and 906. However, those alternatives differ in wattage, and substituting them without confirming the correct wattage rating may affect performance or socket compatibility.