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Generally a stuck open valve means that there is debris trapped inside of the valve. First you will want to locate and turn off the water supply to the irrigation system. Next you will want to find the problem valve out in the lawn. (Valve 6). It could either be debris inside the valve, or a stuck solenoid plunger. Remove the solenoid from the valve, and remove the top of the valve. Also remove the diaphram at this point. Check for any internal debris that may be keeping the valve in the open position. If you do not see anything, put the valve back together, screw in the solenoid hand tight, and if there is a bleeder screw, make sure it is tightly closed. If the valve still will not close, replace the solenoid.

Also, a torn diaphrsgm will create a stuck-open valve.