I know very little about motor vehicles but...
There are too many circuits for the ignition switch to control - too many wires and too much current - the switch would need to be as big as a can of beans - so in the first position the switch operates relays and these relays make the various circuits live.
At least - that's how I think it works. You may have relay problems - they're usually easy to change.
Good luck..., December 2014