Dan,
Chances are that your #3 solenoid is shorted out. You could disconnect the solenoid from the field wiring at the valve and try to turn #3 on from the controller. If you don't get an error message, replace the solenoid.

All Wet
Texas Licensed Irrigator #1897 since 1984

If zone says error that is a bad solenoid. Read about it at http://www.actionirrigation.com/Troubleshoot_sprinklers.html

Here is a link that might be useful: sprinkler help desk