Question
I have a 5 zone system, which was working until yesterday, 4 of the 5 work, but nothing comes from the 4th zone.  Is this an electrical problem?

Answer
It might be.  Check the wire connectors at your valve to make sure they are good.  Replace them if they look corroded.  Make sure the wires are properly hooked to the terminals at the controller.  Try hooking the bad station to one that you know works to see if the valve will come on.  If it does, then yuo have a problem with the controller.  If none of this works, you may need to replace the solenoid on the valve.