September 28, 2023
One of the most frustrating irrigation problems is a zone that simply refuses to turn on. Your controller shows the zone is scheduled. The other zones run fine. But zone 3 — or whichever one it is — stays silent every time.
Before assuming it’s a mechanical problem, verify the controller settings are correct for the affected zone. Common controller issues that mimic a dead zone include: the zone’s runtime is set to zero, the zone is programmed to a different start time, the zone’s assigned program is switched off, or a recent power outage reset the programming.
The solenoid is the electrical component that tells the valve to open when it receives a signal from the controller. A dead solenoid is the single most common cause of a zone that won’t turn on. A technician can test a solenoid with a multi-meter in under a minute.
If the solenoid tests good but the zone still won’t activate, the problem is likely in the wiring between the controller and the valve. Common wiring failures include wire breaks from digging, rodent damage, corrosion at wire connectors, a loose wire at the controller terminal, and wire splice failures.
If the solenoid is good and the wiring checks out, the valve body may be the problem. Valves can fail mechanically in ways that prevent them from opening even when the solenoid is energized.
Occasionally a zone won’t activate because there’s a physical obstruction upstream — a closed isolation valve, debris in the lateral feed, or a collapsed pipe.
If the manual zone test doesn’t identify an obvious setting issue, it’s time to call a professional. Diagnosis of zone problems requires testing equipment, valve access, and experience interpreting test results.