When I hit the button to open the door of my car it doesn't always work. the colder the weather the less it works. I have replaced the battery numberous times and that isn't the problem. I cannot find anywhere online where the part of the car that works the electronic system is located. Seems to be near the drivers door. When I get right up to the door sometimes it works. what worries me is when I need to open other doors or the back. Where is that little part? How do i fix it???