Sorry to state the obvious, but follow the cord and see. It may well be that the external power cord terminates in a junction box somewhere and a separate wire harness runs to the distribution panel. If the place where the cord enters the RV is more than a few feet from the panel, that is very likely the case. The RV maker buys standard power cord packages, typically about 25-28 ft in length, and adapts them to the particular RV layout.
If you have a wiring problem, it may be that intermediate wiring rather than the external cord. Or the connection between them. You just have to hunt for it.