B190 Enthusiasts

Hi, I put this in detail under electrical in an old post but not sure if that is correct format. Basically I'm not getting any juice on the wire that clicks on the isolator. Does anyone know how that wire is fused? I can't find it and I'm about to run a new wire
Thanks! Barry

I'm going to lock this - better to have all of the responses in one thread, or it can get confusing.