Thank you for the info - I will work down the algorithm. I do not believe that this is the last sprinkler in the zone, however. Much appreciated
Is it the last sprinkler head in that zone?
If so, you can do a couple of tests to figure out the problem. You will need to locate your valves or valve boxes.
1. First, move the solenoid from that valve to another. Does it act the same way? If so, this could mean a faulty solenoid. If not, this means your solenoid is fine and you can eliminate it from troubleshooting.
2. Make sure there is no debris under the solenoid. Make sure the solenoid is tight. Make sure that if there is an on/off lever under the solenoid, that it is all the way to the right in the OFF position. Make sure that any bleeds are tight.
3. If the solenoid looks to be fine, shut off the main water. Take the valve apart and look below the diaphragm for debris, clean out. Reseat the diaphragm. If you still have the same issue after taking the valve apart, then replace the diaphragm in the valve.