After the extruder is installed on the printer, you need to connect the stepper motor, heater and temperature sensor to the printer board. We will consider the connection points on the example of the Creality 3D board

We connect the extruder heater to the port of the standard nozzle heater. On the picture it is signed as – nozzle. On other boards, this port can be called as HE0 (heater 0). If the board is designed for 2 or more extruders, then there will be respectively: HE0, HE1, HE2, etc. That is, we need the port with the lowest value, which will mean that it is the first of all.

The same goes for the temperature sensor. It should relate to its heater port. If there are several extruders on the printer board, then there will be the same number of temperature sensors. On the picture we see that the nozzle’s thermistor is indicated by the abbreviation ETEMP. On multi-extruder boards, they can be signed as: TH1, TH2, and so on. Again, select the port with the minimum serial number.

Extruder’s stepper motor we connect to the appropriate port. On this board it is marked with the letter “E”. On multi-extruder boards, they will also have serial numbers E0, E1, etc.

If the extruder’s motor rotates in the wrong direction, you just need to turn the connector with the motor wires on 180 degrees in the port on the board.

If all wires are connected right, on display you will see right temperature of the extruder, and when you press extrude filament - motor's shaft will rotate clockwise, if we look on reare side of motor.