Just got the new Legacy santa fe PA/A set (and B unit). I programmed one PA/A and the B unit just fine. The other A unit does not allow me to program it. To avoid wasting your time with the obvious "did you do this/that" replies: yes there is 18v to track, yes, all the wiring to the track is correct and yes, the unit is in PGM mode. As also mentioned, I just programmed the other two units immediately and perfectly on this same piece of track.
Also, I've never owned a diesel "consist" locomotive. The Lionel manual says to program all units under unique numbers. I've seen some videos however that say to program all units using the same number. If using the same number for all three units, aren't the two A units, which will be opposite facing from each other, going to pull in opposite directions? What do you recommend?
Again, my main and primary concern is getting the A unit programmed and running.
Thanks!