I am not sure what the ERR MC does. However lets say one has a non powered Atlas Providence & Worcester Dash-8 with a Mini Commander - What would it control? Lights? Coupler? And would you try to find out by using the TMCC Cab1 and pressing Aux 1,1?
I have two of these Dash 8's, identical road numbers but one purchased second hand has the MC. Fair warning, I'm taking my trains out after a prolonged storage. The questions are piling up fast.
Thanks gents.
Paul