Your items on your Dashboard are on two different power systems. Your radio, rear TV, and such are powered by your COACH battery system, while your things common to the engine system would be your gauges, gauge lights, are powered by your engine or MAIN battery system.
Either way, when things are cycling ON/OFF it is usually the battery which is not being kept fully charged. SO, check your COACH and CHASSIS battery and make sure it is being charged properly.
If things are continuing to cycle on/off, use a multimeter to check if the voltage on the battery terminals cycles also. IF it dies, then the Charger (for the engine battery) or the Converter (for the Coach battery) is not functioning properly.