Perhaps Colorado law is different, but typically this IS a fix-it ticket.
No, you can't fight this. The officer stopped you for a legitimate reason. The law requires you to have two red brake lights, one on each side... the center one is there for safety reasons but is not a required light.
What you can do, if you find that the officer cited you for the wrong section, is seek a modification of the citation.
What is the Vehicle Code section you were cited for? If cited under 42-4-202, you were cited incorrectly. It sounds like you should be cited under 42-4-208.
42-4-208. Stop lamps and turn signals.
(1) Every motor vehicle or motor-drawn vehicle shall be equipped with a stop light in good working order at all times and shall meet the requirements of section 42-4-215 (1).
42-4-215. Signal lamps and devices - additional lighting equipment.
(1) Any motor vehicle may be equipped, and when required under this article shall be equipped, with a stop lamp or lamps on the rear of the vehicle which, except as provided in section 42-4-215.5, shall display a red or amber light, or any shade of color between red and amber, visible from a distance of not less than one hundred feet to the rear in normal sunlight, and which shall be actuated upon application of the service (foot) brake, and which may but need not be incorporated with one or more other rear lamps. Such stop lamp or lamps may also be automatically actuated by a mechanical device when the vehicle is reducing speed or stopping. If two or more stop lamps are installed on any motor vehicle, any device actuating such lamps shall be so designed and installed that all stop lamps are actuated by such device.
42-4-202. Unsafe vehicles - penalty - identification plates.
(1) It is unlawful for any person to drive or move or for the owner to cause or knowingly permit to be driven or moved on any highway any vehicle or combination of vehicles which is in such unsafe condition as to endanger any person, or which does not contain those parts or is not at all times equipped with such lamps and other equipment in proper condition and adjustment as required in this section and sections 42-4-204 to 42-4-231 and part 3 of this article, or which is equipped in any manner in violation of said sections and part 3 or for any person to do any act forbidden or fail to perform any act required under said sections and part 3.
