A rail cap assembly comprises a rail cap having a first and second opposed ends separated by a length, wherein the rail cap has a top and first and second sidewalls that together form an inner surface extending from the first end to the second end. Openings are spaced along the length of the rail cap. A lighting system is at least partially disposed within the inner surface and comprising a plurality of lighting elements. Each lighting element is secured within a respective opening. The lighting elements are electrically interconnected through connective wiring. The rail cap assembly may be installed one at least one bedrail of a pickup truck.