DVD thru speakers?

I just bought a 2003 Denali and can't figure out how to listen to the DVD thru the speakers. I read the manual but still can't get it to work! Am I missing something? I have the Bose system and factory DVD. I don't have headphones so I don't know if it works that way...my kids are too small for headphones. Thanks for the help!

with mine you have to tune your fm to 88.1 or some other lower fm fequency and it will play through your speakers at least that is how mine works although mine is an aftermarket unit hope this helps

Thank you! The manual didn't mention anything about that!