GMC Safari Back Up Light Bulb Size

The GMC Safari back up light utilizes 1156 and P21W bulb sizes for various production versions. Available information spans a time range from 1985 through 2005.

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
1985-2005	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 GMC Safari uses the 1156 bulb for the back up light across all listed model years, spanning 1985-2005.
The 1156 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard applicable in both the United States and Canada.
The 1156 is a single-filament bulb, which is typical for dedicated back up lights since the function requires only one consistent output state rather than variable brightness levels.
The bulb operates at 12 volts and 21 watts, consistent with standard automotive electrical systems.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a bayonet fitting with a 15mm base width and a single contact pin, distinguishing it from double-contact variants.
The BA15s single-contact base of the 1156 is not interchangeable with the BA15d double-contact base found on bulbs such as the 1157, despite the similar physical housing size. Substituting one for the other is not compatible with the GMC Safari's back up light socket.