White WHM Back Up Light Bulb Size

The White WHM back up light requires a bulb size of 1156 for proper installation and function. Data for the specified lighting component covers the range from 1981 to 1987.

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
1984-1987	1156 (Except Conventional)
1981	1156 (Except Conventional)

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 bulb type specified across all listed model years of the White WHM for the back up light position.
The 1156 is an ANSI-standardized bulb recognized in both the United States and Canada, operating at 12 volts with a 21-watt output and a single filament.
It uses a BA15s bayonet base, which is a single-contact bayonet mount with a 15mm collar. The single-contact design corresponds directly to the single-filament construction, meaning the bulb serves one lighting function only.
The White WHM (1984-1987) and the 1981 model year carry an "Except Conventional" qualifier for the 1156 fitment, indicating that this specification applies to non-conventional configurations of the vehicle.
Because the BA15s base is a single-contact fitting, it is not interchangeable with the BA15d base, which carries two contacts. Substituting a dual-contact bulb into a single-contact socket is not compatible with this application.