This connector seems to come with all JJP machines I've seen. On Stern units there is no question that it is for the optional Slam Tilt switch (PN 502-5032-00).
I shorted it out on a JJP Wizard of Oz machine and it did something with free plays or ?, can't remember. Did not display "Slam Tilt" on the display and end the game[s].
Anyone out there with JJP machines care to try theirs with a bent paper clip? No dangerous voltage there.
Thanks