[Wavery]

On a 14-year-old trailer, that green wire could be almost anything that a previous owner may have installed.

On the other hand, it could be original equipment that just came undone because of those crummy (yellow) twist-on wire connectors.

First thing that I would check is to see if the taillights, brake lights and turn signals all work. Are there any add-on lights on the back of your TM?