radio module is located in the battery compartment, in the "L" shaped plastic carrier hidden under an "L" shaped cover with BMW written on it, right next to the battery.

take the screws out, pull the cover with "BMW" on it out, you will see radio module, the PDC module, the trailer module if you have tow package... take 4 more screws out, pule the carriet out, the cables will prevent you from completely removing the carier out, the radio module is on the left side, with the antenna wire connected and a big, square plug that has smaller plugs inside the big plug...