The LED on your dash illuminates when the running lights are turned on. The power wire for that dash LED is within the umbilical cord from the RV to the Jeep. Plug the cord into the RV, but don't plug it into the Jeep socket. Now, turn on the RV lights and see what happens. If necessary, ground the umbilical cord at the disconnected 6 pin end at the proper pin hole.
If the dash LED does not light, the problem is not within the cord.
If the dash LED lights, the cord is the issue.
Now, if the dash LED does not light, apply 12v to the pin hole at the Jeep end of the cord for the dash LED and see if it lights. It should. This is just a test to confirm the operation of the dash LED. It also will confirm that the dash LED is being powered by the pin in the Jeep, through some feedback from the running lights.
Larry, Eileen, and Finley
2004 Alpine 36FDDS
Third motor home, first Alpine, no need for another.