[CREWZIN]

The P1684 is the signal that the battery has been disconnected in the last 50 starts but a lot of us see that code and haven't touched anything. Looking through the Internet the best advice is to have the whole charging system looked at. Battery stores and some auto stores will do it for free. Even though the battery is almost new, doesn't mean it's not defective with a bad cell or a loose wire somewhere. Before you go, take off the leads and clean the posts to make sure your getting a good connection.