(snip) I have had cars with apparently unsolvable electronic problems. I have known people that got rid of cars after the frustration of trying, even when using theoretically qualified mechanics.
Lin, I tell people that I grew up datin' North Carolina girls, I worked for British companies for 20 years, and I used to be engaged to a redhead -- so I KNOW what frustration is. But I've never been as frustrated as trying to find an "intermittent" electrical problem! I can't imagine everything being run by a little computer.
But that is the point. The system itself points you in the right area for trouble shooting. Usually a problem that is occasional goes away by the time you start to grab your tools to start looking for it. But in this case you can either see the error message or access the memory. Depending on what system malfunctions are identified you can isolate a specific component or system portion that has the malfinction. If one of the modules is acting up, or you think it is acting up, swap it with another one. If the switch relocates a problem it is easy to focus on a bad module, but if the problem stays where it was, then the problem lies with the coach.