What's this plug go to?

[jpspaz]

I just changed my converter and while working through the job I came across a set of wires (green and black) with a blue female connector at the end. It also had a smaller green ground wire coupled with it. I thought maybe I had knocked something loose but I cannot find where this goes. The wires go into the main loom and disappear under the coach. I was thinking that it might have been for an optional item that wasn't installed at build time. Any ideas?