the programming port of this ESC is also the fan port, so you need to unplug the fan first and then plug (one end of) the programming cable in the PRG/FAN port and the other end (of the programming cable) in the ESC port on the LCD program box. Please don’t use the throttle control cable (also called Rx cable) on the ESC to connect the program card/box, otherwise the program card/box won’t function.