The Haynes maintenance manual will have wiring diagrams in the back - I am an apprentice trained instrument and electronics engineer and can just about follow them.
You can buy a Haynes manual in the UK from Halfords and some libraries keep them so I'm told.
Your Ka car problems may be down to Fuse, relay or switch and the Haynes manual will certainly help you discover where the fuses and realys are.
Good luck...
Peccavi
May 2009