Originally Posted by campermatt
If I recall from my PDI, it is just a passthrough HDMI port. In other words, it doesn't actually do anything but pass the signal from the front HDMI port to the rear HDMI port.
I know the rear port of that unit on my 18MT is connected to an HDMI splitter which feeds the HDMI port on the ceiling by where the TV would go, and the outside HDMI port by the TV mount on the side of the TT under the awning.
If yours isn't feeding the TV, I would pull it out and check to make sure the rear port is connected. The bezel around the unit pops off gently with a flat screwdriver under the bottom of it, and there are 4 screws that secure the unit. I watched them pull it out during my PDI, because the original one in my TT was scratched, and I had them replace it.
Pull it off and make sure the connection from the back of the unit is secure along with the connection to the splitter that sends it to the other places you have HDMI ports near TV Mounts. On mine, it's to the outside wall for the outside TV mount and the main living area TV, none in the bedroom.
Way too often the cables are not secure or barely reach and then when they reinstall the radio after hooking everything up, something has come loose. Mine had about an inch of play once I pulled the radio out far enough to see the back of the unit. There was a couple feet of HDMI running from the unit to the splitter but the cord running from the outside HDMI barely could reach the splitter because of the length of the cable running to the main TV had it stretched so far towards that side of the hidden cabinet space.