I battled with the same problem for over a week. Car lights would now and then start flashing and the horn would sound simultaneously. Also, the car locks were opening and closing on their own at the same time as the horn and lights. I tried everything suggested here and more besides. Cutting a week-long story short, the problem turned out to be a failing key fob battery. I unscrewed the fob, removed the round battery and waited... problem solved! *Couldn't believe that such a major problem had such a simple solution. It's worth noting that when I ordered the new battery, I ordered an extra for the spare key fob. It may not work for everyone but it's worth a try. Hope that helps someone.*