its built into the steering wheel, best thing to do to check if thats working is to press and hold the horn button in while turning the wheel.. if the horn cuts in and out as you are turning the wheel then that could be the issue.
sadly Talon is a little.. buried... for me to go and have a look how the horn works. i think the horn gets a constant (or ignition switched) live going to it, and its earth switched via the horn press button in the middle of the steering wheel.
extra earths are always good. theres a 13mm bolt on the back of the intake manifold near the dip stick you can put a cable on and just attach it to the 13mm bolt that does the earthing point under the battery. Talons one is like this extra as well i have a lot of lighting on Talon and they sometimes looked dim when the engine was off but brightened up when i used a jumper cable direct from the engine to body.
still on the hunt for land btw.. i keep getting out bid at auctions! damn economy.. with the devaluation of the £, everyone's sinking what money they have into buying land.. if this was last year or hell 2 years ago i could have bought a whole field!