How do you can you play music through another device using an aux cord

How are you hooking it up? If you are using a USB cord from the phone to the car, most cars cant see the phone as a music device you have to set the phone as a usb storage device and even doing that wont guarantee that the stereo can find the music.

It may be a case of using a Preamp device in line.
You may not have sufficient line current to move the audio from the phone to the aux.

You need to give us more information, for a better answer.

Normally the cord plugs into the green plug on the computer and the line input on the powered speakers.

The iPhone will sync to iTunes on a computer. If the display has a USB port, there must be another USB cord to the computer. The iPhone will go through it to get to the computer.

Try having the device(cellphone.etc..) hooked up to auxillary on its end.. then play music or whatever..then plug the stereo end in and try changing source then.. maybe the unit isnt switching because it doesnt think theres a reason to.. not kidding.. Ive seen this kindve stuff all the time from electronics..theyre so smart theyre stupid. Hoefully this works:)

Check the connecting cords of the sepakers. It may not be in healthy condition or not properly connected. You may use your earphone to cross check it.

try playing your music first on your phone then with the cord alreay in your radio, plug it in to your phone....If that doesnt work, might be a setting on your radio....is it on aux in????

you need a aux cable to do that...one end goes to ur ipod or music player and the other end of the cable goes to your aux input

Im not a techy, but i know enough bout music to know what 2 do. If your car stereo has a AUX imput 3.5mm jack, (headphone-like-cord) you need to connect your Vibe to the cord and the cord to the AUX imput. then make sure that ur car stereo is set to AUX. when it does, the vibe most likely will be on pause or wat ever setting you left it on prior to connecting it. Now all u need to do is.....Selec the song or playlist, and press PLAY.