Having trouble with my right blinker

Thanks for the replies so far, here is what i have found so far.

I followed the trailer connector to where it disappears into a black junction box. Turns out the bown wire is the right turn/brake, the red wire is the left turn/brake, green is the taillights. Yellow is nothing. So I have power to the brown/brown junction, where the brown wire disappears into the floor. Where it exits at the taillamp, there is no power.

So I am guessing there is a break in the brown wire at some point where it is buried in the trailer. Would it be a lot of work to unearth this wire, or would running a fresh wire back to the tallight be okay?

Thanks again!