Rain Bird RD 600 Flashing FUS: Short Circuit Diagnosis

Rain Bird RD 600 Timer Flashing FUS: Wiring or Solenoid Short

A Rain Bird RD 600 timer displays flashing "FUS" and won't activate sprinklers. Fuse appears intact visually. The FUS code indicates a short circuit in field wiring or a solenoid coil.

Most Likely Culprit: Backflow Preventer Solenoid

If the system has an electric backflow preventer (master valve), its solenoid is a common failure point. Replacement cost ~$8 at home centers.

Troubleshooting Steps

1. Check for recent digging near valve boxes (wire damage)
2. Replace backflow preventer solenoid first (lowest cost, highest probability)
3. If persists, test each zone solenoid resistance (20-60 ohms)
4. Inspect wire splices in valve boxes for corrosion/water intrusion

FUS Code Meaning

The RD 600 monitors current draw on each zone. Excessive current (short) triggers FUS display and shuts down output to protect controller circuitry.

Wire Inspection Tips

• Look for nicked insulation from edging/trenching
• Check wire nut connections for moisture/corrosion
• Verify no wires pinched under valve box lids