Hooking up galaxy S to car radio via usb.

Hey all,  I have a galaxy S GT-I9000M using firmware 2.2
I downloaded some songs onto phone (show up on music player).  I want to use my USB to hook into radio in truck but I cannot get any sound on truck radio when hooked up. I can play songs on music player on phone, but not on radio. (pioneer with usb)

Am I missing something?

Hi guys i have been at this for a while now using my computer, windows needs aditional usb drivers for your phone.

Car stereo via usb needs devices to use generic drivers.

So how i got my phone to work on car stereos any model using usb cable is this.

Use a program from market that will allow you to create a folder inside your external SD Card
I Used ROOT Explorer and created Folder named Music on root of external SD Card.

Now from the Internal SD Card Copy/Move all your music files to the new folder created inside the External SD Card.

Thats that piece done.

No change USB Settings on phone.
If you have USB Debugging on need to turn this off.
App Drawer/Menu > Settings > Applications > Development > USB debugging UNTICKED

now thats done we need to make phone readable on car stereo.
Car stereo needs to see the phone as Mass Storage like it does with USB Pens/Flash Drives
App Drawer/Menu > Settings > Wireless and Network > USB Settings > Mass Storage.

Thats now done.

Now start up the car stereo system.
Connect USB to Car Stereo
Switch Source to USB if needed
Connect Phone to USB Cable
You Should get a screen that asks you to
Connect storage to PC
Click this and the phone will mount SD Card to stereo.

Last step is the only annoying thing about doing this.

But it should now work and play your music.

This way does give you better sound than connected to an AUX Cable.

Thanks and Enjoy the Music