I re-opened my sprinkler system this season to discover that one of the zones would not go off on it's own. After visually inspecting the valves, I see that the issue is that one of the two wires that connects to the problem zone's solenoid has been severed. Not sure what happened - maybe an animal chewed through it or weather destroyed it, but it is severed right near the solenoid connection, making standard splicing and fixing impossible from what I can tell.
How do I fix this? Do I need to solder the wire back on? That was the only thing I could think of, but wanted another opinion before taking any irreversible action.