I can't help you on the wiring diagram but I can tell you that I am having similar issues finding some info such as adding fog lights. These vans are new to us and quite frankly, no one is really advertising them out here in Phoenix. Sure enough, there will eventually be more how to's and opinions as this van gets more into the mainstream.
I would like to know this too. As I wanna add an 8 inch sub under the drivers seat and some tweeters to the doors. But I gotta know the colors on the harness for the speakers so I can install a line converter.
Lads, one of our members purchase the Electronic Service Manual (esm) which is what Nissan use for repairs and maintenance. It might be worth dropping him an PM. He may well be able to upload the wiring diagrams, maybe.