You definitely need to see the "W220 S-Class Owners Start Here" sticky at the top of the forum. Scroll down to post #36 for a version of the "Encyclopedia" that is uninterrupted by people who don't read.
You will find discussion of the SAM under "Electrical System." SAM means "Signal Acquisition Module." It is in fact a kind of router for switch input, sensor input, and system operation. If you come across discussion of "Electronic Fuse" be aware that they are a component of the SAM, and they are circuits, not fuses in the common usage.
Last edited by Skylaw; 01-18-2011 at 11:58 AM.