Hi I have a early 2007 GP and I was having some headlight trouble. I was driving along with headlights on and they would switch to main beam on there own and I couldn't get them off this would also happen when I put main beam on I took it to fiat they replaced the coms unit behind steering wheel and dryed my fuse box and and that fixed it for nearly a month but the problem is back but this time the horn is sounding on its own and the headlights will not turn off no matter what settings they are in or if the car has the key in or not. Fuse box is dry because fiat tryed to fob me off with me jet washing car was problem but I have not even washed it since having it back. I am completely lost does anyway have the foggiest idea what is wrong or a similar problem which maybe be linked. Please help lol.

Thanks

OK, a long shot.
My daughters Suzuki swift was doing equally silly things, you could be driving along and the interior light would come on randomly, the doors would lock themselves and then unlock again, and do this a number of times.
In the end we narrowed it down to only happening when it was raining, or if we'd washed it.

I eventually found the problem.
The windscreen seal was leaking, water was running down the inside of the "A" panel and into the cars electronics.