Hardi RD-600 Shows "OFF" After Valve Repair: Controller or Wiring Fault?

Why Controller Displays "OFF" When Activating Repaired Zones

After replacing diaphragms and solenoids on two backyard valves, the Hardie RD-600 flashes "OFF" instead of running those stations. This means the controller detects a short circuit and shuts down output to protect itself.

Diagnostic Steps

1. At the controller, disconnect the wires for the two repaired zones from their terminals.
2. Run those stations manually.
3. If "OFF" stops flashing and other zones run: Problem is in the field wiring or new solenoids.
4. If "OFF" still flashes with wires disconnected: Controller internal fault.

Common Wiring Mistakes

• Solenoid wires touching each other or ground at the valve box.
• Wire nuts not fully seated—strands bridging adjacent terminals.
• Using the wrong common wire (must be the same white wire used by all other valves).

Next Steps

If field wiring checks out, test each new solenoid with a multimeter (20–60 ohms). A shorted solenoid will read near 0 ohms. Replace any defective units.