Note: The horn normally has a constant live feed and the horn button on the steering wheel merely connects the other horn terminal to earth. So start by applying a multimeter between earth and each of the terminals on the horn to see if you have a live one. If so, briefly connect the other terminal to earth and see if the horn works. If it does, then it’s possible that the earth connection has come adrift in the steering wheel. If it doesn’t and you have established that a live feed is present, then its probably the horn itself.
Standard fitment is around £10 from the likes of Holden.
