Try this first as per Hunter Industries themselves...
described here.
The controller does not respond to all stations. Example, the controller has 12 stations but the display will only go to 6 stations. Controller does not recognize modules. Turn off the power to the controller and <b>remove the battery</b>. Check all module connections to the controller. Remove the module and reinstall. Power the controller back up. The microprocessor will recognize all modules.
Sprinkler Solutions, Inc.
Arizona and Colorado
www.sprinklersolutions.net