Your computer in the vehicle does two things. I collects information from sensors, then the computer uses this information to control the engine components to run the engine, Etc. If the light comes on, it is either the computer is looking for information that it is not getting, it is trying to control something that will not respond. Only an OBD II scanner can read the codes.
RV manufacturer will not be able to help you with codes, you need to get information from Chassis maker. Once I know code number I type in Mfg., year and code on internet. Then you may be able to find solution.
Auto place scanners are very generic, and sometimes I have to go to a Mfg. dealer to solve problem.