As I understand it (so take it for what it's worth) the jobcom is a sperate box mounted on the sprayer that plugs into the existing wireing harness at that point and no extra wires come into the cab. Sprayers that have the steerable axels have one , I'm not sure what other features require one. I just know I don't have one.
I'm in the middle of researching this for my sprayer also, so I haven't actually done it yet. Hope I'm not giving you inacurrate information but this is my understanding of how it works.