When you do the aux mod, you have to splice into the cd player harness. To listen to music through the aux port you have to have a cd in the player so it plays, but the music being played from the cd is so faint that when you have your aux source hooked up and playing it covers over the sound from the cd. So the cd plays but its hard to hear even when you raise the volume up. It's kinda hard to explain I guess.