So I've located bcm, the middle plug, and on that middle plug i've located the only dark blue wire.

After cutting it I have to attach an extension wire to the 2 inch blue wire that is still connected to the socket/plug that plugs into the bcm. Right?


Then the other end of the blue wire (which is no longer connected to the bcm because I cut it) I just tape off with black tape. Right?

Yep, you just ground the end that's attached to the plug.