Hopefully this thread will address a few concerns that I had had since owning the w221 interface module. I would like to first add that this module seems to be very old. If this module does not come with import or option to update through USB. The board on this module has 4 switches with two positions that are on specified in any of the owners manuals. This module was installed on a 2007 Mercedes Benz s550 with non rear factory camera The first concern that I am having in regards to the installation instructions. Particularly when placing the 120 resistor between the high can Lo can wires. The instructions instruct installer to place between pins 1 and 2 on the radio side of interface. This is where it left me and the installer baffled. Instructions are as followed.

2. Solder supplied 120 ohm resistor across CAN
High and CAN Low, Radio Side of interface
harness (Pins 1 & 2)

Could we be more specific as to where these wires are exactly located. There can be confusion in referencing these wires as such. For instance radio side would imply that these wires are located on the vehicle harness. But locations 1 & 2 involve a yellow wire and also a black and white striped wire. When referring to the interface module harness this leads us to two yellow wires one solid one striped. If we could be more specific on the placement it would be much appreciated.
Edited 02.10.2015 2:45 PM