Dave, I said that half in jest. I have no idea what those little surges would do to the tester (if anything) and I don't intend to try to find out.
I do see this device as having the potential to ascertain the source of doubletoot. I noticed that no signal went out from my TIU when the second toot occurred. Haven't had a chance to see what happens on the other TIU. This does require a loco to be powered up.