When a sprinkler system won’t turn on, check power, water supply, controller settings, rain sensor lockouts, and valve or wiring faults first.
If your lawn is dry and the heads stay silent, don’t panic. Most no-start problems trace back to simple issues: a tripped outlet, a closed shutoff, a paused schedule, a rain sensor lockout, or a single faulty part. This guide walks you through clear checks in the right order, with quick tests that separate easy wins from deeper faults.
Why Your Lawn Sprinklers Won’t Start: Fast Checks
Work through these items from fastest to slightly deeper. Stop as soon as you find the fault.
Power And Reset Basics
- Confirm the controller display is on. If blank, restore power at the outlet, reset a tripped GFCI, and check the controller fuse.
- If your timer has a battery, swap it. A weak battery can wipe schedules or block starts on some models.
- Perform a soft reset per your model’s manual. Keep your schedule handy in case you need to re-enter it.
Water Supply And Backflow Position
- Open the irrigation shutoff fully. Many setups have a separate shutoff before the backflow device.
- On the backflow, the two ball valves should be parallel with the pipe. If they’re crosswise, the line is closed.
- If winterized, be sure any drain cocks are closed and the main is pressurized.
Program, Start Times, And Seasonal Adjust
- Make sure a real start time exists for the active program. One start time runs the whole list of zones; stacking multiple start times can delay or block runs.
- Confirm days to water aren’t all off. Skip days or blackout dates can look like a dead system.
- Seasonal adjust at 0% stops output. Bring it back to a reasonable percent for the season.
Rain, Freeze, And Soil Sensors
- Rain sensors hold the system off after a storm until the disc dries. If the sensor LED shows active, slide the bypass switch and test a zone.
- Freeze and soil probes can also block starts. Use the controller’s sensor bypass to test.
Manual Valve Test
- Find a zone valve box. Twist the solenoid a quarter turn counterclockwise. Water should flow within seconds.
- If water flows by hand but not by timer, suspect wiring or programming. If nothing flows by hand, suspect a closed main, stuck valve, debris, or no pressure.
Quick Diagnostic Table
| Symptom | Likely Cause | Fast Check |
|---|---|---|
| All zones silent, blank display | No power, tripped GFCI, blown fuse | Reset GFCI, replace fuse, confirm outlet |
| All zones silent, display OK | Shutoff closed, backflow closed, sensor lockout | Open valves, bypass sensor, run manual |
| Manual runs; auto won’t | No start time, wrong days, seasonal at 0% | Add start time, pick days, adjust seasonal |
| One zone dead | Bad solenoid, cut lead, clogged valve | Swap solenoid, ohm test, clean diaphragm |
| Zones skip or stop mid-run | Low pressure, pump issue, flow sensor cut-off | Open main, check pump, review controller alerts |
Step-By-Step: Get From No-Start To Running
1) Verify Power, GFCI, And Fuse
Start at the plug. Press the GFCI reset on the outlet or upstream bathroom/garage circuit. If the display is dim or flickers, try a different outlet. Many controllers include a small glass or blade fuse; replace it with the same rating.
2) Confirm The Water Path Is Open
Open the irrigation shutoff all the way. On a typical double-check or PVB backflow, both handles should line up with the pipes. If you hear water charge the line and the pressure gauge rises, you’re ready to test a zone.
3) Run One Zone Manually At The Timer
Use the controller’s manual function for a single station. Pick Zone 1, run three minutes, and watch the heads. If heads pop and spray, the system is capable of running; you’re likely chasing programming or sensor gates.
4) Bypass The Sensor Input
Flip the sensor bypass on the controller. If there’s a wired rain switch on the fascia, slide it to bypass. Run the same zone for one minute. If it starts now, the sensor is holding the system off. Dry the rain sensor or replace it if stuck. The EPA explains how labeled controllers and sensors manage watering in its page on WaterSense labeled controllers, which also helps prevent waste by pausing cycles when conditions don’t call for water.
5) Check Program Start Times And Days
Many timers run nothing if the program has no start time. Make sure Program A (or your active program) shows at least one start time, and that watering days aren’t all off. If you use multiple programs, avoid overlapping start times that fight each other.
6) Test A Valve At The Box
Twist the solenoid a quarter turn to open by hand. If water flows, the plumbing is fine. Tighten the solenoid back snug and trigger that zone from the controller. No response now points to a bad solenoid coil, a broken common wire, or a loose splice.
7) Inspect Splices And Measure Resistance
Lift wire nuts in the valve box and check for corrosion. Replace with gel-filled connectors. With power off, measure resistance across the valve leads. A typical 24-VAC valve reads around 20–60 ohms; an open reading suggests a break, while near-zero ohms points to a short.
8) Clean Or Rebuild A Stuck Valve
Shut water at the irrigation shutoff. Remove the valve bonnet, lift the diaphragm, and rinse debris. Check the tiny bleed hole and spring. Reassemble carefully and test again. Manufacturer guides show this clearly and match the process above. Hunter’s help page for “automatic program not starting” explains programming checks that often look like hardware faults.
When Every Zone Stays Off
If nothing runs, even by hand at the controller, you’re looking at a global gate. Run these checks in order.
Controller Locked Out
Some smart timers pause output during sensor events, flow alarms, or pending updates. Bypass sensors, clear alerts, and try a single-zone manual run. If heads run now, restore your normal sensor settings last.
Closed Main Or Backflow
Trace the pipe from the controller toward the yard. Verify the main is open and the backflow valves are parallel. If you have test cocks, a brief crack should show water; no flow here means the main is closed ahead of the backflow or the supply is off.
Broken Common Wire
All valves share a common. A cut in that return wire disables every zone. If manual valve opening at the box works but the controller won’t fire any zone, inspect common splices and any recent trench work. Re-splice with gel connectors and retest. Trade tech notes and field guides routinely point to the common as a top all-zones failure point.
Master Valve Or Pump Start Not Engaging
Some systems use a master valve or pump relay. If that device never opens, downstream zones can’t pressurize. Listen for the relay click at the controller at start. If silent, check the MV/Pump terminal, the relay fuse, and the master valve coil.
When A Single Zone Won’t Start
One dead zone is nearly always local: a bad solenoid, a broken lead, or valve debris. Swap the suspect zone wire at the controller with a known good zone. If the dead zone now runs on the good terminal, the controller is fine and the fault sits in the field wiring or valve.
Solenoid Coil Check
Disconnect the two solenoid wires and measure coil resistance. Readings near infinity indicate an open coil; replace the solenoid. If resistance is normal, reconnect with new gel nuts and try again.
Diaphragm And Seat
Grit can wedge the diaphragm. Rebuild kits are inexpensive and quick to install. Keep parts brand-matched so the screw pattern and diaphragm align.
Programming Pitfalls That Feel Like Hardware Faults
- No start time on the active program: Manually runs work, schedules never fire. Add one start time only.
- Start times stacked: Program A and B both at 6 a.m. can create long delays or cancel behavior on some models.
- All days off: Easy to do after a vacation mode or seasonal pause.
- Seasonal adjust at 0%: The timer thinks you want zero output.
- Sensor set to “active”: A rain, freeze, or soil device can hold the system off until conditions clear.
Valve, Wire, And Sensor Specs At A Glance
| Part | What To Expect | DIY Fix Time |
|---|---|---|
| Solenoid Coil | ~20–60 Ω; audible click on energize | 10–20 minutes |
| Diaphragm | No tears; clean bleed hole; seated spring | 20–40 minutes |
| Common Splice | Waterproof gel nut; firm tug test | 10–15 minutes |
| Rain Sensor | LED or switch shows “active” after storms | 5–10 minutes to bypass |
| Backflow Handles | Both parallel with pipe when open | 1–2 minutes |
Pro Tips That Save Time
Use Manual Start At The Valve First
Opening a valve by hand proves water supply and valve health fast. If it runs by hand, shift to wiring and programming. If it won’t, stay in the box and rebuild before chasing wires.
Isolate By Swapping Wires
Move the suspect zone wire onto a known good station terminal at the controller. If it runs there, the board is fine and the field side needs work. If it still fails, the issue stays with the field parts tied to that zone.
Keep Sensor Bypass Handy
Rain and soil devices save water by pausing output until conditions change. They also cause head-scratchers after a storm. The EPA’s Rain Sensors tech sheet explains how these devices intentionally interrupt a scheduled run until the disc dries or the timeout ends, which can look like a fault when it’s just the sensor doing its job.
Safety, Care, And When To Call A Pro
- Shut the irrigation main before opening a valve body.
- Cut power at the controller before meter testing leads or moving splices.
- Label wires as you go. A small photo saves time during reassembly.
- If a pump relay buzzes or trips breakers, stop and call an electrician or irrigation tech.
Smart Fixes That Prevent The Next No-Start
A few upgrades reduce head-scratching and water waste. Weather-based timers and soil sensors modulate run time when conditions don’t call for water. EPA’s criteria for labeled controllers confirm performance targets around efficiency and scheduling logic, which helps keep landscapes healthy with fewer false starts or lockouts.
Seasonal Startup Checklist
- Open the main and backflow, then pressurize slowly.
- Bypass the rain sensor for the first test run, then restore it.
- Run each zone for two minutes and scan for leaks, stuck heads, and weak pressure.
- Set one clean start time, pick sane days, and dial seasonal adjust to match the month.
What To Keep In Your Kit
- Gel-filled wire connectors and a small roll of 18-gauge irrigation wire
- Multimeter, spare fuse, spare solenoid, diaphragm kit, and a screwdriver set
- Valve box key, Teflon tape, and a soft brush for cleaning valve parts
Troubleshooting Flowchart
Display off? Fix power → Display on? Open main/backflow → Manual run at timer? If yes, fix program/sensor; if no, open valve by hand → Runs by hand? Fix wiring/solenoid; if not, clean or rebuild valve.
Common Myths That Waste Time
- “If one zone runs, the controller is fine.” Not always. A single bad output driver or shorted lead can kill a specific station while others run.
- “Rain sensors only stop runs during a storm.” Many hold the system off until the disc dries, which can take a day or two.
- “More start times water more.” One start time runs all stations in order; adding more repeats the entire list, which can clog the schedule and mask faults.
Quick Wins You Can Do Today
- Open the irrigation shutoff and align both backflow handles with the pipe.
- Add a single clear start time on your active program.
- Bypass the sensor for a one-zone test, then re-enable it.
- Rebuild one suspect valve with a fresh diaphragm and new gel splices.
Results You Should See
After these steps, you should be able to trigger a single zone and hear the valve click, see heads lift, and watch an even spray. A clean schedule should run without stalls, sensors should only pause during wet or cold spells, and the controller should display each station change on cue. If the system still won’t start after power, water, sensor bypass, valve test, and wiring checks, call an irrigation technician and hand over your notes; you’ve already done the smart triage.