Guessing that when you say you have a controller on the steering you mean a ATU,  An ATU will disengage after several minutes of inactivity, meaning if you haven't touched the monitor and changed a page or any other thing to tell the system you are still awake it disengages, this can be set to either Activity Monitor or seat switch. very few systems ever have the seat switch connected so it is set to activity monitor, to keep it active you can simply touch the resume switch every so often to tell it you are still there. as for why it is re-engaging and then dis-engaging you can go into the diagnostics page and drop the menu down to autotrac diagnostics to see what the last exit code tells you, this has to be done before trying to re-engage the steering.