Geeetech

Hello,

i just bough a Prusa I3 pro B, freshly mounted, X Y Z axes works correctly, but when i try the extruder it don't work

i plug the extruder engine on the X connector on the mainboard, the extruder engine works,
i plug the X engine on the extruder connector on the mainboard, the extruder engine don't work

i try to switch the stepper driver (a4988) between them, the extruder engine don't work
i try to turn the potentiometer on the stepper driver, the extruder engine don't work
i try to change the cable, the extruder engine don't work

i upload the latest firmware, the extruder engine don't work

do yo have some idea where my problem com from ?

So you didn't heat up the extruder in the entire test procedure?