Question
6 zone irrigation system.  5 zones work great, however, pump cycles on and off repeatedly (one 2-3 seconds/off 2-3 seconds) when one zone is activated throughout entire duration of cycle.

Answer
Hey Richard, I hope this helps. If I'm understanding you right, one zone runs the entire time the other zones are running. I think this one valve (the one that is running all the time) is stuck on, or has a short in the controller. To tell if it is the controller, or the valve itself, simply find the valve that is sticking on, and disconnect the wires from the solenoid. Then run a cycle, if it still runs with the other zones, then it is the valve itself, If it doesn't run, then you have a problem in the wiring or the controller. I would suggest going to this website: www.irrigationtutorials.com and it will show you how to rebuild or replace your bad valve. Let me know if I can be of anymore help, thanks and have a great day.