yup if the "key on" is activated with anything involving the air bag system unplugged it will fault and that's the quick way to get it to figure out everything's fine once you hook everything back up. i had to do this when i put in my D3 and then again a few weeks ago when i forgot to hook up the passenger seat after taking both out for cleaning. works like a champ
it's the same for frontier's, just with Key On, Engine Off cycles instead of the push button thing