Epson 3865X Plus - Manual (Page 289)

Mouse Problems
If you are having a problem with your mouse, you may see one
of the following error messages:
8601 AUXILIARY DEVICE FAILURE
8602 AUXILIARY DEVICE FAILURE
8603 AUXILIARY DEVICE FAILURE
If you see one of these messages, make sure that your mouse is
completely connected to its port on the back of the computer.
Also, be sure that you have connected it to the correct port. For
example, you may have connected the mouse to the keyboard
connector instead of the mouse connector. Even though the
mouse connector fits into the keyboard port, you cannot use
that port to run your mouse.
If the mouse seems to be connected properly, check the
documentation that came with your mouse to see if there are
any special procedures you need to perform to use the mouse
with your computer. Also check for troubleshooting
information in the documentation or contact your dealer.
D-28 Troubleshooting