I was given this engine that someone had taken apart thinking the motor was bad.  I tested the motor and it runs; but, there are two wires in the bundle of 6 black wires that goes from the tender to the engine.  There is a circuit board in between and if you hold the board looking at the non-printed side with the black wires down, the two wires, looking left to right, would be the second and third wires - were does the other end hook to? 

It would be great if someone had a schematic diagram for this engine and could send it pdf.