Toyota Repair: 1999 4-Runner trailer wiring, trailer wiring harness, left turn signal

Question
Hello,
I own a 1999 Toyota 4-Runner with a factory towing package. The terminals on the original trailer wiring connector corroded so I replaced the original connector with a new one. When I checked the new connector everything was fine except that I had no power to the left turn signal\brake lite terminal of the connector. I checked all the new splices with a continuity tester and they were all ok. I also checked the trailer wiring harness to were it enters into the body in the left rear and that looked fine. Also, somewhere there must be a converter for the trailer lights since the vehicle has separate turn signals and brake lites and the trailer wiring is a 4 wire system. The lites on the vehicle itself work fine so I must have a bad connection or connections somewhere. So my questions are: Where inside the body does the trailer wiring harness plug into the main wiring harness? Where can I find the converter that converts the trailer wiring to a 4 wire system, could this be bad? Are there separate fuses somwhere for just the trailer wiring? Is there some kind of master connector somewhere that I may have bad connections for the trailer wiring and my rear window defog since I also noticed that my rear and side window defog quit working. The rear and side window defog are on the same circuit as the heated mirrors which still work. The fuse for this circuit looks ok. Any help you can give me on where to look for these problems would be greatly appreciated so I don't have to pull the whole interior apart looking for these connectors.

Thanks for the help,
Dan Jaski

Answer
The most common problem is the tailight converter, the converter is not available seperately from toyota, I recommend replacing the entire trailer towing harness which comes with the converter, the converter is located behind the left tail light, remove both tailight assemblies to replace the harness,it should be obvious where the connectors and the converter are located.