What's up everyone,

My name is Matt, and I'm going thru absolute HELL with my 2014 Nissan Maxima SV. The wiring harness comes thru the firewall and then plugs into this changeover junction box where the wire colors switch to different colors(for the most part). Well, the junction box itself is completely corroded with most of the pins not having contact anymore. Plus many of the wires have previously been spliced (horrible splicing job) and have failed as well.... My question is, since the harness is only damaged at this one location just inside the vehicle near the firewall, should I repair the wires, purchase a new junction box or just purchase and replace the entire harness???