Just went out and checked mine in the dark, I swear there was a hose running out of it running somewhere down below. I'll take a picture of it tommorrow morning.

 

I did not see a option for using it in the FSM, but they did reffer to blowing air into that port while cleaning.

 

Just for the record, mine is plugged as well. Its been that way for about 2 years atleast since it was that way when I got it. I'd say cap it, but then again people tell me I'm an idiot. Haha.

-Keith

 

Hey thanks for all the responses. I guess it's supposed to be capped from what everyone says. My dad suggested it might just be something for Toyota to test out the vacuum to whatever that connects to. I'll plug it when I can pick one up. Thanks again, that had me pretty worried.