What is AUX IN ?
AUX IN ( Auxiliary) is the port for Audio input interface, it is 3.5mm port.
In the package of our BMW Android screen, there is an AUX Cable (photo showed as below). The function of this AUX cable is to switch the Audio from the BMW Android screen to factory car speakers. Because the BMW Android screen don't have the amplifier inside, it need to use BMW factory sound system,thus it need to connect the AUX cable,otherwise, it will no sound output
PS: For the car made in 2017-2018 (with EVO menu),it don't have AUX IN, they have USB port. Thus the BMW Android screen without AUX cable, the sound go via USB.
How connect the AUX cable ?
Please kindly check the wire diagram as below. The AUX cable, one side connect to the AUX port (Audio out) from the new power harness, an other side is connected to the AUX IN port under the armrest box (For most of BMW car, the AUX IN port under the armrest.