Trailer Light Connector - No Right Brake / Turn Signal Light

[mjquillici]

To begin, I know that the problem is not with my trailer, because I have no problems when connected to other vehicles.

When hooked up to my 4Runner, all of the lights work, except for the right brake/turn signal light. I have no idea wheat the problem is. It's making me crazy. If the problem is with my 4Runner, then I don't know how best to troubleshoot. . . . .

 

[mjquillici]

Any ideas? I'm wondering if the trailer light converter box may be dying.

Do you all know where this is located???