Ray Lombardo posted:MTH engines can be finicky when they are first added. In addition to the good advice above, I would take all the other locomotives off the track. Sometimes, when adding a new MTH locomotive, the presence of other DCS locomotives or TMCC locomotives causes problems. Why, I am not sure but it does.
Yes I agree use a programming track or follow Ray's advice.... This could be a simple ID conflict& hopefully the engine remains dark & silent when it first receives power indicating it's seeing the dcs signal.