I have a Lionel Century Club II 6-28069 NYC 4-8-4 Niagara Steam Loco & Tender in for repair. After repairing the universal joint, everything works fine. Except when you press #6 on the handheld instead of blow down, I get a diesel horn.
Must be a special option on this model.
It is programmed as Eng#24, Set, Aux1, 7,4.