I swapped the drives, but it does the same if connected to the internal port.
I played with the drive some more and found out that the motor will start by its own if it is rotated in some positions.
I took some voltage measurements that confirmed this, as sometimes there is 12V present on the one green 3-pin cable that goes from PCB to the motor. If the 12V is present, then the motor will start.
The presence of 12V varies on the rotation of the motor, so it comes and goes about 6 times in one rev. It looks like there are some hall sensors that detect the position of the rotor.
I played with the drive some more and found out that the motor will start by its own if it is rotated in some positions.
I took some voltage measurements that confirmed this, as sometimes there is 12V present on the one green 3-pin cable that goes from PCB to the motor. If the 12V is present, then the motor will start.
The presence of 12V varies on the rotation of the motor, so it comes and goes about 6 times in one rev. It looks like there are some hall sensors that detect the position of the rotor.