Two Zones Run Simultaneously: Diagnosing the Cause

Symptom: Zone 1 Activation Also Opens Zone 2

When zone 1 is triggered (manually or automatically), zone 2 also runs. Three possible causes, tested in order:

1. Controller Output Short (Most Likely)

Disconnect zone 2 wire at controller. Run zone 1. If zone 2 stays off, controller has internal short—replace controller.

2. Field Wiring Short

Reconnect at controller, disconnect zone 2 wire at valve. Run zone 1. If zone 2 stays off, zone 1 and 2 wires are touching underground. Locate and repair the short.

3. Valve Mechanical Failure

Manually open zone 1 valve (turn solenoid CCW 1/4 turn). If zone 2 activates, zone 1 valve has a ruptured diaphragm allowing water into zone 2 line. Replace zone 1 valve.

Diagnostic Order

Start at the controller—it's easiest. Work outward. Most common cause: controller failure.