Toro System Multiple Zones Fail: Controller Port Voltage Testing

Toro Sprinkler System: Only 2 of 8 Zones Work After 10 Years

A 10-year-old Toro system suddenly has only 2 working zones. Solenoids and diaphragms swapped between working/non-working zones—no change. Working zones function from controller; non-working zones don't respond manually or electrically. Manifold has water throughout.

Diagnosis: Controller Output Failure

Since hydraulic components test good (swapped and working zones stay working), and non-working zones fail both manually (bleed screw) and electrically, the issue is likely controller output ports not sending voltage to specific zones.

Voltage Testing Procedure

1. Set multimeter to VAC (24V range)
2. Black lead on Common (COM) terminal (white wire)
3. Red lead on suspect zone terminal
4. Activate zone at controller
5. Reading should be ≥24VAC

Interpreting Results

• No/low voltage: Controller port damaged. Try unused port if available (RD 600 has 6 ports).
• Voltage good: Test at valve solenoid. If voltage there, solenoid/diaphragm issue. If no voltage, wire break.

Controller Reset Attempt

1. Power off controller
2. Disconnect backup battery
3. Wait 10 seconds
4. Power on, reconnect battery
5. Test zones again

Replacement Consideration

If reset fails and multiple ports dead, controller replacement needed. Rain Bird ESP-Modular (~$90 for 4 zones) is a reliable, modern alternative.