The manual for this set pre-dates Legacy, but contains the correct instructions for assigning the engine and tender a new ID. If you check the manual it says (on p. 12) that the default setting for the IDs is 1 (engine) and 2 (tender) BUT it also says that the set comes factory-programmed as a TMCC “Train” with a default Train ID of 9. Have you tried operating it that way? If the IDs have been changed, which is possible if the set is used, they should answer TMCC commands using those IDs but to work together correctly the units have to be operated as a Train. This has a separate Info setting in the CAB2. Remember that unlike Legacy, TMCC is limited to a total of nine trains with Train IDs 1-9.
Note also that there is one other early TMCC quirk about this set: under TMCC the smoke units have to be switched off manually, otherwise they will keep running when there is power to the track - they don’t turn off when you just shut down the sound system using the remote. This is not an issue in conventional of course because the power to the track is cycled on and off.
‘Way back when this set was issued, Lionel published a supplemental manual explaining the smoke system operation in TMCC. It, the main manual and a wiring diagram can be accessed on the Lionel product page: http://www.lionel.com/products...-turbine-73-6-18149/
The only other thing that occurs to me is that you might have set it up in the “Info” settings as a Legacy engine/Train when it is in fact TMCC and won’t answer Legacy commands. It should be set to TMCC control in both the engine IDs and the Train Info. Mine didn’t function right when I first set it up but I retraced all the steps, the Train setting took and it ran like a charm.