1999 Toyota 4Runner Question: 1999 4runner no power to right turn signal of trailer lights

When I hook up my boat trailer I get all lights on left side of trailer, but only tail lights on right side, no turn signal or brake lights. Went under truck and stripped a litte wire and and tested, no voltage to green turn signal light. Yellow, left side is good. Is this a broken wire at some point or other harness issue? Took 4 runner tail lights out to look for wiring harness attachment no luck, is it buried under a panel somewhere? thanks