I hope Micheal corrects me if I am wrong, but these newfangled gauges are a mini computer network.
all the sensors plug into ONE main control box under the hood. then the individual gauges are wired in series to each other and to the main control box. each guage then gets the signals it needs from the control box. its really slick and clean that way. kinda like a home network router feeding all the computers in your house.
no mechanical gauges piping into the cab.