Error Code XEROX Error codes reference

I'm looking for a reference to all the error codes a xerox machine could give.
Currently, the user manual has a quite reduced amount of error codes, but i find it insufficient for most of the times.
Where can I find a way to know what any error code could mean?
Sometimes, an error code is something so simple as comm error due to an unplugged module, but the error code does not indicate it by itself!
I´m not asking for a full repair reference guide (if i could get it it would be nice) but a simple reference on what any error message could mean, even if it's just a clue, would be more than enough.

Thanks!