I know of two ways, one is relatively simple, there other a bit more complicated. The relatively simple metod is to remove the cable connection and the front TV connection at the switch box. Using a coupler, connect the 2 coax cables together, then try to get the cable channels on the front TV. If this is successful the problem is in either the switch box or the connections at the switch. If unsuccessful, there is most likely a problem with either the cable or the park connection.
The more compicated method is to run a coax cable from the coach outside cable connection up to the area of the switch box. Remove the cable coax from the switch box. Using a multimeter set to ohms, test the shield from the two coax cables, then the internal wire from the two coax cables. If the wire is OK, you will see a very low reading on the meter for both tests. If there is no reading on either test, the cable is defective. and must be replaced. If the cable is defective, you can get by by running a different coax cable from the park connection to the switch box maybe through the drivers side window. This will allow the systems to operate until you can figure out how to rerun the internal cable. Hope this helps.
Jim and Lynda, (Sophie, Jake, attack trained killer Shi-Tzus :-))
2003 Fleetwood Expedition 38N 2005 Saturn Vue