Intermittent Master Valve Fault on Toro Ecxtra Controller

Controller Faults on MV/Pump Circuit After Several Cycles

A Toro Ecxtra controller with a 1 HP pump and pump start relay runs 1–3 cycles, then faults on the master valve circuit. New wire from controller to relay didn't help. Swapping zone wires didn't isolate the issue.

Likely Cause: Aging Pump Start Relay Drawing Excess Current

As relays age, their coils can draw more current, triggering the controller's sensitive overcurrent protection intermittently.

Two Fixes

1. Replace the pump start relay with a new unit of the same rating.
2. Add an intermediate control relay: Wire a small 24 VAC relay (e.g., a "ice cube" relay) to the controller's MV/PUMP output. The small relay's contacts then switch the pump start relay. This isolates the controller from the heavy coil current.

The intermediate relay is a low-cost, reliable solution if you prefer not to replace the pump start relay immediately.