How to Use AUX in a Car

By Quinten Plummer

Just like the tape decks and CD players that preceded MP3 players, cassette adapters have been replaced by the more efficient "AUX," or auxiliary, port on car stereo units. Instead of routing the output from your external audio source through the stereo's cassette player and then having the stereo play the cassette, the "AUX" port routes the signal directly into the car stereo for a cleaner connection.

Connect your mobile device to your car's AUX port using a 1/8-inch-to-1/8-inch audio cable. Plug one end of the audio cable into the "headphone" port on your mobile device and the opposite end to the AUX port.

Press the "AUX" button on your car stereo or toggle the input button to select the "AUX" input.

Set the volume on your mobile device to about 50 percent, then start the device's music player. Control the master volume level using the car stereo's volume control.