Troubleshooting "1 FUS" Error on Richdel 446PR Controller

If your Richdel 446PR controller displays "1 FUS" and the system stops watering—only to resume partially when you press the pause/semi-auto button—you're likely dealing with a zone 1 wiring or solenoid fault. The "FUS" message indicates a short circuit detected on that specific station.

What "1 FUS" Means

The controller's built-in circuit protection has detected excessive current draw on zone 1. This typically points to either a faulty solenoid, a damaged wire, or a poor connection at the valve. The fact that other stations run when you override with the semi-auto button confirms the controller itself is functional; the issue is isolated to zone 1.

Step-by-Step Diagnosis

1. Inspect wiring at the controller: Disconnect the zone 1 wire from the terminal strip. With the controller powered, activate zone 1 manually. If the "1 FUS" message disappears, the fault lies in the field wiring or valve.
2. Check the valve box: Locate the zone 1 valve. Examine the solenoid wire connections for corrosion, cuts, or loose splices. Repair any damaged wire with waterproof connectors.
3. Test the solenoid: Using a multimeter, measure resistance across the solenoid leads. A healthy 24 VAC solenoid typically reads 20–60 ohms. Readings near zero indicate a short; infinite resistance means an open coil.

Replacing a Faulty Solenoid

If the solenoid tests bad, replacement is straightforward:

1. Shut off the main water supply to the irrigation system.
2. Unscrew the old solenoid (counter-clockwise) from the valve bonnet.
3. Disconnect the two wire leads, noting which connects to common and which to zone 1.
4. Install the new solenoid, ensuring the plunger moves freely.
5. Reconnect wires using waterproof wire nuts or gel-filled connectors.
6. Turn water back on and test zone 1 from the controller.

When to Call a Pro

If the fuse message persists after solenoid replacement, the issue may be a nicked underground wire. A professional with a wire tracer can locate the fault without extensive digging. For most homeowners, solenoid replacement resolves the "1 FUS" error and restores full automatic operation.