Mercedes ml 280 08 plate

Hi again guys. So I'm having the problem of back brake light staying constantly on, heaters that have blown & not the fuse plus was on without the key in the ignition, and the file gauge defective by saying 3 quarters full when it's actually full. Someone here mentioned the SAM module which is now looking to be the issue. I've googles searched and found that there's two SAM modules front and rear, is this correct? If so, giving my faults, does that mean that both my modules need replacing?