Isuzu Trooper Back Up Light Bulb Size

Additional Notes

• The Isuzu Trooper backup light bulb specifications span the 1984-2002 model years, with two distinct bulb sizes appearing across that range: the 1156 and the 1073.
• The 1156 bulb is the predominant fitment, covering the majority of model years including 1984-1991, 1993-2002, with the exception of 1986, 1989, and 1992.
• The 1073 bulb applies to the 1986, 1989, and 1992 Isuzu Trooper, making those three years distinct from the rest of the production run in terms of backup light specification.
• Both the 1156 and 1073 are ANSI-standard single-filament bulbs rated at 12 volts, sharing the same BA15s bayonet base configuration.
• The BA15s bayonet base is a single-contact design, which is the defining physical characteristic that distinguishes it from dual-contact bayonet bases used in other automotive bulb types.
• The primary technical difference between the two bulb types is wattage output: the 1156 operates at 21 watts, while the 1073 operates at 13 watts, making the 1073 a lower-output variant.
• Because the 1156 and 1073 share the same BA15s base, they are physically interchangeable in terms of socket fit, but the wattage difference means they are not specification-equivalent replacements for one another.
• Both bulb standards are recognized under ANSI classifications applicable to the United States and Canada, indicating standardized production tolerances across manufacturers.