There are a couple of things that cause a stuck valve:
- Sand or grit in the rubber diaphragm
- Worn diaphragm
- Bad solenoid (not usually, but sometimes)
Turn off the water to the mainline.
Get a screwdriver and remove the top (bonnet) of the valve.
Inspect for debris in the rubber diaphragm. Rinse the diaphragm if you see debris.
Check to see if the rubber is worn.
Put The valve back together.
If this does not work, take the top of the valve and internals down to an irrigation distributor.
Buy a new valve of same brand and model.
Rebuild the valve with new bonnet, solenoid, diaphragm and spring. You now basically have a new valve without cutting out the valve.
Troubles arises when it is a very old valve that is no longer manufactured or it is an oddball brand like Orbit or Lawn Genie. With these cut out the valve and replace with any Hunter, Irritrol or Toro valve. I saw way too many warranty issues with Rain Birds DV.
Hope this helps. Another idea is to disconnect the wire for that valve, but usually the valve continues to run because the valve is stuck.