Coaxial cable outlet - passenger side

Cable TV outlet on passenger side - I apologize if this has already been addressed in this forum, but my search was unable to locate it. I plugged a TV into the outlet via a coaxial cable but was unable to get the TV to display what was playing on the TV's located inside the cabin. The owners manual didn't give too much direction either. It may be a TV problem but wanted to check with the forum before I dismounted another TV. Any advice would be greatly appreciated. Ellisu2015