Car stereo systems with an "AUX" or “auxiliary” input make it easy to connect an MP3 player or other audio device directly to the system for playback. Many older BMW models did not have an "AUX" input installed as standard, but with the help of an aftermarket adapter you can add an input to almost any BMW factory stereo system. When you are finished, you can place the input jack almost anywhere in the vehicle to easily connect your devices.
Use a wrench to loosen and remove the negative battery terminal. This ensures that no electricity is going to the stereo system while you are working.
Use the trim removal tool to pry the trim away from the dash, starting with the area above the glovebox. Slowly work your way toward the trim above the stereo. Remove the trim piece. If you do not have a trim removal tool, wrap electrical tape around the tip of a flat-head screwdriver to remove the trim.
Pry up and remove the trim piece above the stereo.
Remove the screws on each side of the stereo using the screwdriver, then pull the stereo out from the dash.
Press the tab to release the large black connector and remove it from the back of the stereo.
Press a flat-head screwdriver against the blue tab on the connector and pry it upward to release the smaller connectors.
Insert the gray connector from the "AUX" input kit into the empty portion of the black connector, then replace the other connectors and lock the blue tab back into place.
Thread the other end of the "AUX" cable into the opening in the dash and down through the back of the dash so that it comes out in the floor area of the passenger side.
Insert the stereo back into the dash and replace the two screws, then replace the trim pieces. Reconnect the negative terminal on the battery.
Plug one end of the 3.5mm cable into the "AUX" input jack and the other end into your audio device. Turn on the stereo and select “AUX” as the input type. You should now hear the audio from your device coming through the speakers.
