Lawn Genie Timer Replacement: Testing Zones and Identifying a Master Valve

An old Lawn Genie Richdel R416LG timer failed. While awaiting replacement, the owner tried manually powering one zone (24VAC between common and zone wire) but got no response. The wiring diagram shows a possible pump/master valve connection, and an extra wire is present (4 zone wires + common for 3 zones). No power wire is visible at the solenoid location.

Diagnose Before Digging

1. Check the controller's MV/P (Master Valve/Pump) terminal: If a wire is connected there, a master valve or pump start relay exists.
2. Test with MV/P energized: Apply 24VAC to both the zone terminal and the MV/P terminal simultaneously. Many systems require the master valve/pump circuit active to supply water to zone valves.
3. If no wire on MV/P: The extra wire may be unused or for a future pump. The system likely has no pump.

Locating Buried Valves

If the above fails, use a valve locator (chatter tool) or trace wires from the controller. Digging blindly is a last resort.

Most residential systems with a pump use a pump start relay, not a buried pump. The relay is typically near the controller or pump.