I have basically the same motorhome.
Is your problem with the original Intec black & white monitor installed in the dash? If yes, running over something in the road is probably not the problem as the wiring runs above the headliner. If I remember correctly, the Intec had a switch to make it stay on all the time. If that switch was off, then it only came on when the coach was placed in reverse. Maybe the switch on yours is defective, or a wire inside the case to the switch has broken. I would first verify that you have 12 volts coming into the Intec monitor. I believe it may have an inline fuse on it somewhere near the back of the monitor. If you do not have 12 volts there but are getting 12 volts from the reverse sense line I think you would have the symptoms you are describing. Look at the link below and go about half way down the page to see a typical wiring diagram (for a later model Intec but yours is probably similar).
intec wiring diagramI removed my Intec and replaced with a color LCD monitor (and new camera). If you have to remove the monitor, it drops out behind the dash and is somewhat difficult to remove due to all the other wiring and obstructions. I pulled mine out through the center console after removing the drawer.
If this is a replacement monitor/camera where someone has run new wires under the coach, then the road impact damage could be a factor, but the power feeds are still under the dash. The replacement monitors will typically have two inputs as described in a post above...one 12 volt switched with ignition and another 12 volt that is hot only when the coach is in reverse (which is like the diagram in the link referenced above).
I hope you find your problem.
Fred
