No real need to slide the switch to program unless your changing the engines ID number. It must be in the run position to start up and move. All TMCC engines are delivered with 1 as the ID.
Have you ever run these using just TMCC ?
Did you purchase just the base only and plan on using just your DCS remote to run them ?
You mentioned that the base was on. I'm guessing you plugged it into the wall. Just make sure it is a properly grounded 3 prong outlet.
By any chance are you running more than one TIU. The last thing I believe that's asked when adding a TMCC engine into DCS. Is that you must assign it to the TIU the TMCC base is plugged into.