I would also start by checking the back of the power amp. plate to make sure both TV are properly connected (see above diagrams). If that is not the issue, you will have to trace the coax for the second TV to make sure it is not shorted out or if an "F" connector has come loose, which is not an uncommon problem. If you can't locate the problem, maybe your amp. is not powering both TVs and may need to be replaced. You didn't say if it used to work OK and this is a new issue, or an issue with a new trailer. If that's the case, take it back to the dealer.