Sprinkler Controller Not Working: Blank Screens, Errors and Missed Cycles

The controller is the brain of your sprinkler system. When it fails, zones may not run at all, may run at the wrong times, or may run nonstop. Some controller problems are simple to fix; others mean it is time for a replacement. This article walks through the most common controller problems and how to troubleshoot each one.

Problem 1: Blank Screen

Check the power

Most residential controllers plug into an outlet through a transformer or have one wired inside. Check that the outlet has power by plugging in a lamp or phone charger. Garage outlets are often on a GFCI circuit that can trip. Look for a GFCI outlet with a reset button in the garage, on an outside wall, or in a nearby bathroom.

Check the transformer

The transformer converts household power to the low voltage the controller uses. If the outlet works but the controller is blank, the transformer may have failed. Some controllers have a fuse or circuit breaker inside that can trip after a short on a valve wire.

Check for damage

Heat, moisture, insects and power surges can all damage controllers. Look for burn marks, corrosion or insects inside the housing. Fort Worth thunderstorms can bring lightning surges that damage electronics.

Problem 2: Lost Program

If the controller loses its program after a power outage, the backup battery is likely dead. Many controllers use a 9-volt or coin-cell battery to keep time and settings. Replace it once a year. Newer controllers often store programs in memory that does not need a battery, but the clock may still reset.

After replacing the battery, set the date and time and review the program. Our controller programming guide walks through the settings.

Problem 3: System Does Not Run on Schedule

If the screen works but zones do not run when they should, check:

• The dial or mode setting. Make sure it is set to Run or Auto, not Off.
• The rain sensor. If the sensor is wet or faulty, the controller will hold off watering. Many controllers show a symbol when the sensor is active. Our article on rain and freeze sensors explains how to test it.
• Rain delay. A rain delay may have been set and forgotten.
• Watering days and start times. Confirm the program has days and at least one start time.
• Seasonal adjust. If it is set very low, zones may run for only a few seconds.

Problem 4: Zones Run at the Wrong Time

Check the clock, including AM and PM. After a power outage, some controllers reset to a default time. Also check for extra start times or programs you did not intend. Running between 10 a.m. and 6 p.m. is not allowed in Fort Worth, so a clock set twelve hours off can cause a violation.

Problem 5: A Zone Will Not Stop

If a zone keeps running even after you turn the controller off or unplug it, the valve is stuck and the controller is not at fault. If the zone stops when you unplug the controller, the controller may have a stuck output. See our guide on a zone that will not turn off.

Problem 6: Error Messages or Fault Codes

Many controllers report station faults, such as a short or open circuit. A short often means a damaged wire or a failed solenoid. An open circuit often means a cut wire or a disconnected solenoid. Check the controller manual for what each code means, then see our guide on a zone that will not turn on for testing the wire and solenoid.

Problem 7: Several Zones Fail at Once

If several zones stop together, check the common wire connection at the controller. A loose common terminal can take out every zone. If the common is tight, the damage may be in the field, where the common wire runs to the valves. Our article on valve wiring problems covers how technicians trace it.

Repair or Replace?

Replacing a controller makes sense when:

• The display or buttons have failed
• It has been damaged by a surge or moisture
• Station outputs have failed and cannot be repaired
• It is old, hard to program, or lacks features you want
• Parts are no longer available

Fort Worth’s irrigation code requires that repairs or alterations that replace an existing controller include operational rain or moisture and freeze shut-off technology. When replacing a controller, make sure the system has a working sensor or equivalent technology. Our article on smart controllers covers one common upgrade path.

Protecting Your Controller

• Mount it out of direct sun and rain if it is not rated for outdoor use.
• Keep the housing closed to keep out insects and moisture.
• Replace the backup battery yearly.
• Consider a surge protector for the outlet.
• Take a photo of the wiring so you can reconnect it correctly after any work.

Before You Replace It

Write down your current program before you take the old controller off the wall: each program’s watering days, start times and each zone’s run time. Label every wire with the terminal it came from, or take clear photos from a couple of angles. Note any sensor wires and any jumper between the sensor terminals. With that information, moving to a new controller is straightforward, and you will not have to rebuild the schedule from scratch or guess which wire runs which zone.

When to Call a Technician

If you have checked power, battery, programming and sensor and the controller still is not working, our sprinkler repair team can test the controller and wiring and repair or replace what failed.