Sound isnt working!

[qwertmonkey]

I just put some LCDs in my car. I got em hooked up and the picture is bright and clear. The only problem is that I can't hear anything! The volume is up all the way and all the cords are hooked up, and the connections are tight. There are the AV cords, (red, white, and yellow) There is one cord that I did not use, it looks like it would plug into a headphone hack. They do have built in speakers. I can hear it if I plug in some headphones.

Is it not getting enough power?
What am I doing wrong?  ??? ??? ???

 

[audioguru2]

An LCD is a type of display, not a product.
Which product did you install in your car? A DVD player?

I think the audio input is the headphones type of plug but what is it supposed to be plugged into?

What is at each end of the AV cords?