iveco cargo 75e15 1989?

there is no power to the starter solinod, managed to work out the power to the starter relay switching side is there on the second stage of ignition switch, but not at the third stage. if i put 24v to the relay it will start. I dont know why it's loosing the feed when the ignition is at the third stage. does anyone know where i can get a wiring diagram from.