henw, I'd take the stereo cover apart. About three minutes and three or four screws and you can see for yourself what's back behind the stereo. Really, it's easy. If you have the factory A/V upgrade, you will have a switching input box back behind the stereo. Maybe it's unplugged. If for some reason you don't have it, you can buy one at Crutchfield about $85 bucks or so and hook up the existing prewired RCA cables from the TV to stereo cavity.
Chris and Christina- Boerne, TX / Evergreen, CO - TAC TX-7
2008 27'FB Int'l Signature CCD