Dodge D100 Back Up Light Bulb Size

Additional Notes

• The Dodge D100 uses the 1156 bulb for the back up light position across all specified model years, spanning 1975-1979 and 1984-1989.
• The 1156 is an ANSI-standardized bulb type, meaning its physical and electrical specifications are governed by a recognized North American standard shared across the United States and Canada.
• The 1156 operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard incandescent automotive reverse light applications.
• The 1156 is a single-filament bulb, meaning it serves one lighting function only, as opposed to dual-filament types that handle two functions such as braking and running light from a single housing.
• 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 its single-filament construction.
• The BA15s bayonet mount is a twist-and-lock style base, secured by two side pins that seat into a socket without threading. This is a widely used base type in automotive lighting.
• Because the 1156 carries a dual-contact equivalent known as the 1157, the two are not interchangeable despite their similar appearance. The 1157 has a BA15d base with two contacts, and installing it in a single-contact socket intended for the 1156 would result in improper fitment.