Passenger side taillight

My passenger side taillight is not working and has not for several months now. I have replaced the bulbs and that did not work. I tried cleaning the connectors in the socket and on the assembly and that did not work. I removed the sockets and tested them on another light assembly to confirm whether or not they were the issue they all worked fine in a different light assembly. I even bought a whole new assembly thinking the assembly itself was the problem, but when plugged into the same wiring for the passenger side taillight the new assembly did not work either. So now I am down to either the wiring or the fuse. However, it does not make sense that it is the fuse because the driver side taillight works just fine and both lights are on the same fuse, from what I understand. That leaves just the wiring, but I cannot find any instructions on how to address this problem. I am desperate for any input or advice on what the problem may be and how to fix it, plus Ia m well aware that the problem may be something I have not tried or suspected yet. By the way I just spent over $1,000.00 on brakes and other repairs on this car so I am trying very hard to avoid the mechanic with this problem. I also was raised working on cars since my grandfather owned a garage so I am not afraid to do any work and know my way around a car good enough to do most smaller jobs myself.