To check for a draw, you need to hook up a meter inline with the battery, or use an amp clamp. Then you need to latch the hood latch, and the driver door latch, and lock up the vehicle so that it will go to "sleep". In sleep mode, it should draw less than .002A- it may take up to 2 minutes or so for it to fully drop into sleep mode. There's so much operating when it is "awake" that it is not possible to accurately check for a draw.
Most common problems are with the radio- aftermarkets hardwired to the battery, or the factory 6 disc changer in the trunk if installed, but sometimes the stock stereo head.