Try a search on here or Google. I remember reading about that fault several times on here. It's nothing too tricky to fix as I recall, some resistors perhaps.
Someone who's had the problem will be along soon with the proper answer, just give it a while.
Thanks erneboy. I think I've solved the problem after searching the whole of google, plus the Fiat forum and many others. I just thought I might be a help to others with a similar problem as it's apparently such a "common" fault.