Cushion Battery

I have a Renault Clio 1.1.The horn is not working from behind the wheel.?
We have tried the battery and works.We believe the fault is in the direction wheel.With air mattress there we are not trying, so to be included in the garage.Any ideas what the fault could be and how much it would cost.
You had better ask the garage before I took it. If it is working on the battery, the fuse has blown, probably just a contact that needs cleaning.