Depending on the manufacturer of the valves being used in the system, most solenoids are available and replacable. First thing to do is disconnect the lead wire from #4 from the clock and fire that station. If the "fuse" function doesn't go on alert, reconnect the wire, locate #4 valve in the field and do the same thing there. If the fuse function works again, you pretty much know the solenoid is at fault. If the solenoid is disconnected and the fuse alert STILL comes on, there's a short in the field wiring... Hope there's another free wire in the harness coming to the valve manifold.
The Irrigation Specialist Mfg' Az.
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