I have the same problem , i am simply putting in a new horn and linking it to the ciggie lighter, the horn is placed just under the battery, jack the passengers side up and look under the arch the horn is just there you will just have to look around a bit but belive me its right there, anyway open the hood and up on the right hand side there is a place where a new horn can bolt on away from engine, havent worked out how to run the wirs yet but i have a push button for the switch im putting it in the dash, it works and conforms to pass the m.o.t . just need to find a plce to run the wire to the dash, shouldt be hard tho, ill let you know, apart from that my ka 2002 touch wood is sound as a pound.
darren, November 2008