Rain Bird SST-400i Zone 3 Error and Simultaneous Operation: Wiring Cross-Check

SST-400i Shows "Error Zone 3"; Zones 1 & 3 Run Together

This indicates a wiring cross between zone 1 and zone 3 field wires, or a controller output fault.

Steps

1. Check valve‑box wiring: ensure zone 1 and zone 3 hot wires are not twisted together.
2. At the controller, disconnect zone 1 and zone 3 wires. Activate zone 1 and measure voltage on both zone 1 and zone 3 terminals. Only zone 1 should read 24 VAC. If zone 3 also reads voltage, the controller is faulty.
3. If controller tests good, the cross is in the buried wire—locate and repair.