Make that supply house.

Guess I should have read the thread about the 2-4-4-2! The 2 pin connector is for track power from the locomotive to the tender. Since the tender has pickups for track power too, I suppose all those pickup points should insure non-stop power so "keep alive" units are unnecessary.
I agree with the 2-4-4-2 analysis of the 4 pin connector.
Now if we could just figure out the exact part description for the 2 and 4 pin connectors so we could get them from an electronics puppy house, we would be in business when we break one.   

There are 2 plugs between the tender and the locomotive on the 4-4-0 units equipped for DCC. It appears to me that the 4 pin connector carries the motor + and - as well as the headlight + and -. I cannot figure what function the 2 pin connector does. Can anyone provide an answer?