Ok had some time this morning to play around with this.
AUX 2 does not toggle between Acela TMCC and Acela Legacy option. It turns the headlights on and off.
As jon says Acela TMCC mode is the correct one. Acela Legacy mode must be for the new Legacy Acela that was droped from the catalog?
Have to say that this is a nice train once you get the ir couplers lined up correctly.
Fun to take apart as I got this secondhand I fixed the pantographs as they had come out of their slots and one of couplers needed fixing.
Little lad loves it. We were running his two favourite trains the Hiawatha and the Acela today.
Regards
Nick