As @GregtheBike said, we'll have to wait till he comes back and explains, but I think you're probably right. I checked mine and it is 3 pronged. I completely forgot that it was there, because it blends in so well.I think he is asking about something else.
On the right hand side of the transmission hump between the hump and the seat bolster, there is a square fabric patch attached with velcro. Under that patch is some kind of connection, It may be three pronged, but I can't see it. I removed the patch and I could feel it. (the car was off, and I didn't get electrocuted)
I have no idea what this connection could be for.