Mystery Wire in Battery Compartment
 

I was changing the battery in my '06 LR3 SE today. When I'd removed the old battery, I noticed a wire/plug dangling near the firewall. After a moment's search, I found it's receptacle and re-connected it.

I don't believe the wire was disconnected during my battery installation. I think it had been disconnected for quite a while. I haven't noticed anything different after reconnecting it. Does anyone know what it is for? I've posted a picture here:
https://www.dropbox.com/s/ll7g4eqxgz...0Wire.jpg?dl=0

Thanks!