When using a control board with parallel-wired Z-axis motor ports, you may encounter a situation where one of your Z-axis motors turns in the opposite direction of the other. This can cause your gantry to bind or move unevenly.
Because the Z-motor ports on the board are wired in parallel, they share the same driver and firmware signals. This means it is not possible to independently reverse the direction of just one motor through firmware settings. Any change in the firmware would affect both motors equally.
The most effective and straightforward solution to this issue is to physically reverse the wiring order for the single motor that is turning in the wrong direction. This is done by swapping the pins in the JST-XH connector on the motor cable that plugs into the board.
By reversing the order of the four wires, you effectively reverse the polarity of the motor coils, causing it to spin in the opposite direction without affecting the other motor.
The diagram below illustrates the process of swapping the pins on your 4-pin JST-XH motor connector. The goal is to completely reverse the order of the wires.
As shown in the guide, you will need to move each wire to its opposite position:
To do this, use a small, pointed tool (like a small flathead screwdriver or tweezers) to gently depress the metal locking tab visible through the slot on the connector housing. While holding the tab down, pull the wire backward out of the housing. Once all wires are removed, re-insert them into their new positions until they click into place.
After re-pinning the connector for the affected motor, reconnect it to your board and test the Z-axis movement. Both motors should now turn in the correct, synchronized direction.
