'95 trailer light problem (HELP!!)

HELP!!!!

Ok, the trailer is 100% ok. Checked with a different vehicle. My initial problem is that the wires on the Toyota end are coroded. Cut them back to where they are just coming out of the Toyota, and found 2 good wires, 2 bad wires. The bad ones are the ground and the Right side. Ground, no problem....can run a new dedicated ground. Right is a problem. Removed the right side tail light...was able to see the trailer wires through a little hole behind the tail light....where's my grabber....
Got them! Cut wires at that point. Good ground! Good Left! Good Tail!
Right side is dead still.

I am tempted to splice in to tail light assembly to power my right side.
Of course, Toyota has separate bulbs for brake and right turn signal...
so I would have to splice into both and put diodes in there to stop them from interfering with each other. This should work...but I don't know what will burn out since the trailer does suck a few amps.

New idea....get on internet and search for people with similar woes. Maybe find someone that can tell me where those 4 wires go on the
4runner..... Found this forum, and the posts involving this converter box for trailer lighting issues. Can anyone tell me if this sounds like a new converter box might fix me as well? Also, where is my box located??

TIA

Raoul

Just a follow up...

The problem was indeed the converter box. It was a bit different, as when I measured the output of the box for the right turn signal, I only got 5V instead of the 12V. Anyway, the box was located on the passenger side of my 4Runner, but was an aftermarket one. Put in a generic one from Checkers for 14 bucks or so and all up and running.

-R

Good job!