Battlefield 3 doesn't include classical cheat codes support. There is no console window or any other similar imput, where you can enter the "magic" word and get the corresponding option activated. That's how they developed the game, and there's no future update which will add this feature. Almost every PC gaming site out there will actually offer Battlefield 3 cheats, but instead of traditional list of codes, they will give you a bunch of tips and tricks on how to unlock secret stuff and achievements (the most stupid and uselles thing). The word CHEATS in video game industry stands for unlimited health (god mode), stamina, weapons, armor, items, and the other similar things, and it should stay that way.
If you want to enable real cheating for Battlefield 3, go and get yourself a good trainer within the TRAINERS section of our site.