If I put it in the "middle" setting, ie not permanently on or off, then the light stays on when I start the ignition and stays on. If I turn the ignition off, get out of the car, and lock it etc, after 10 mins, the light is STILL on. This didn't happen with the Fiesta, and so I'm assuming it's a fault. I've opened the bonnet, boot, and all doors, and closed them to see if that's the problem, and it still happens. So maybe a faulty sensor somewhere, if it's not the fuse?