A trailer illumination assembly includes a trailer that has a plurality of running lights disposed on the trailer. The trailer includes a power source is positioned in the trailer and a female light plug which can be electrically coupled to a male light plug on a towing vehicle. The female light plug is in communication with the plurality of running light. An adapter plug is pluggable into the female light plug when the female light plug is not electrically coupled to the male light plug on the towing vehicle. Additionally, the adapter plug places the power source on the trailer in electrical communication with the plurality of running lights on the trailer. In this way the running lights on the trailer can be powered by the power source on the trailer.