White/GMC WXLL Back Up Light Bulb Size

The White/GMC WXLL back up light requires a bulb size of 1156 for the rear lighting assembly. Available information covers the period from 1988 through 1995 for the specified vehicle.

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
1988-1995	1156

Bulb Specifications

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

Other Locations

Additional Notes

The 1156 is the sole back up light bulb size listed for the White/GMC WXLL across all model years in the specifications, spanning 1988-1995.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which is consistent with its application as a dedicated back up light.
It operates on a 12-volt electrical system and draws 21 watts, placing it in the standard incandescent range for automotive reversing lamps.
The 1156 uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, distinguishing it from the dual-contact BA15d variant.
Because the BA15s base has only one contact pin, it is not interchangeable with physically similar bulbs that use a dual-pin bayonet base, even when the outer housing appears comparable.
The 1156 conforms to ANSI standards recognized in both the United States and Canada, indicating the bulb meets a defined performance and dimensional specification shared across North American markets.