Buick Skyhawk Back Up Light Bulb Size

Additional Notes

• The Buick Skyhawk uses the 1156 bulb size for the back up light across all model years listed in the specifications, spanning 1975-1982 and 1984-1989.
• The 1156 is an ANSI-standardized bulb recognized across the United States and Canada, meaning it conforms to a defined set of electrical and physical standards shared across manufacturers.
• The 1156 bulb operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard automotive reverse lighting applications.
• The 1156 is a single-filament bulb, meaning it serves one lighting function only, as opposed to dual-filament bulbs that can serve two functions such as braking and running light simultaneously.
• The 1156 uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width. The single-contact design corresponds directly to the bulb's single-filament construction.
• The BA15s bayonet base is not interchangeable with the BA15d base, which is a dual-contact variant used on different bulb types. Substituting one for the other is not possible without a socket modification.
• The consistent use of the 1156 across the Buick Skyhawk's listed model years indicates that a single bulb specification applies to the back up light position throughout the vehicle's production run as documented.