TMCC coupler keeps opening

The problem could be either mechanical or electrical in nature. Disconnect the wiring for the problem coupler to the board to diagnose the cause of the problem. If it still opens, the problem is mechanical. If it does not open, the problem is electrical.

Larry

If it is electrical you add a non polarized 1uf cap across the coupler wires.  IF your unit has TAS internals the one I have seen had the caps already.  If this used all Lionel parts (Motherboard), you may need to add the caps.  G

I disconnected the coupler wire. No uncoupling has occurred. At the time being I will run it like that. That Engine does very little to no switching anyway. When time presents itself I will try and dig deeper into it. G not sure I understand the whole cup thing.

It reduces the noise that triggers the couplers.  Lionel started adding them to the motherboard on later models. It is 1uf 35 or 50V NP cap.  You solder one leg onto each terminal leg, or if there is room under the Motherboard you can put it on the legs of the connector under the board.  One cap for each coupler.  G