Our sprinkler system had trouble this summer. After replacing the sprinkler controller and finding out that our problem was a faulty master control valve, I have learned a lot. Newer sprinkler systems have a master control valve that has to open every time a zone valve does. This is a good thing usually to prevent leaks, but also gets used A LOT more than other valves, so it wears out faster. You can test each zone with a multimeter for voltage to see if that zone has a fault. You can use and ohm meter to determine continuity on each zone's wiring as well. If you have developed a short, like we did, you may see fluctuations in both voltage and continuity. Our new sprinkler controller is smart and was able to report back that there was a fault on either the master control valve or each and every zone it tried to run. Because the master control valve showed up on every error report, we started our troubleshooting there....