Jeep CJ5 Back Up Light Bulb Size

Additional Notes

• The Jeep CJ5 back up light specifications span model years 1959 through 1983, with the 1156 bulb designated for the majority of those years.
• The 1156 is an ANSI-standard single-filament bulb rated at 12 volts and 21 watts, fitted with a BA15s bayonet base, which is a single-contact base with a 15mm collar.
• The 199 bulb shares the same BA15s bayonet base, voltage, and wattage as the 1156, and is classified as a variant of it under the ANSI standard.
• The Jeep CJ5 is specified with the 199 bulb for the 1973 and 1977 model years, while all other listed years call for the 1156.
• Because the 1156 and 199 share the same base type and electrical ratings, the physical and electrical interface between the two bulbs and their respective sockets is effectively identical.
• Both bulb types carry ANSI standardization applicable to the United States and Canada, meaning their specifications conform to a defined industry standard rather than a proprietary sizing system.
• A single-filament design, as found in both the 1156 and 199, means the bulb serves one lighting function only, which is consistent with the dedicated role of a back up light.
• The BA15s bayonet base uses a single contact pin offset, distinguishing it from the BA15d double-contact base used in dual-filament applications, so substitution with double-contact bulbs is not applicable to these fitments.