I decided to attempt to make sense of the EMS-220 (Engine Monitoring System) wiring. I had a couple of goals by doing this. First, since this was the only cable not labelled I wanted to be sure I had the correct wire bundle. (it is the right one.) Next, for routing purposes, I wanted to separate wires going forward thru the firewall and those that are aft of it. Then I wanted to identify each of the wires so that I could label them and get them to the right location. In doing so, I found many unidentifiable wires. Working with Advance Flight Systems, they were very patient and helpful, I was able to identify a few more. Due to time limitations, I'll have to call them back again. Also, there are many wires/pins that aren't used, so I guess I'll have to do continuity checks to see what's what.