On most Belt driven machines, the slave Y Axis motor is mounted facing the opposite direction as the primary Y axis motor. In this configuration, you want to reverse the direction of the Y2 motor's rotation, to ensure that it runs the correct direction. This is easily achieved by simply reversing the wiring order on the Y2 Motor's terminal as shown below

IMPORTANT WARNING: Note: Never connect/disconnect motors to a powered-up controller. Always turn off power before connecting/disconnecting accessories to/from your BlackBox

Note if you are not using OpenBuilds Motors, refer to FAQ: Identify Motor coils to identify the coil pairs. The color codes shown above only apply to OpenBuilds Motors