sprinkler system malfunction??

I have a 8 zone rain tree sprinkler system I've been using for a couple years, and until today everything worked perfectly.
Today zone 2 comes on with every zone.
I've changed the time for zone 2 to zero, but that did not stop it.
I disconnected the wire for zone 2 - that did not stop it.
I have temporarily turned my system off until I can correct this issue. Any help will be greatly appreciated.