I always assumed that this was a battery vent hose, but it started slipping and dragging on the ground. I thought maybe it had gotten disconnected, but when I pulled the plastics to change the battery, it just fell out. The previous owner had installed an Odyssey dry cell battery. Now I'm thinking that maybe he just left the hose in place in case he ever went back to a conventional battery. I can't find anything else in my repair manuals.