21 Troubleshooting & Maintenance Practice Questions & Answers

1. 1. A technician places an ohmmeter across a controller's station 3 terminal and the common terminal, and the display reads OL (over-limit). What should the technician do FIRST?

   • A.Separate the solenoid from the field wires and retest the solenoid alone✓ Answer
   • B.Order a replacement solenoid for that valve and install it right away
   • C.Replace the controller output board, since an open station means board failure
   • D.Raise the meter's range setting and record that second reading instead

   An OL or infinite reading taken at the controller covers the whole circuit: the station wire, both splices, the common and the coil. Isolating the solenoid and reading it by itself tells the technician whether the open is inside the coil or out in the buried wiring, so no part is replaced before the fault is located.

   Source: Irrigation Association, Electrical Troubleshooting Student Workbook — isolating a solenoid from field wiring before condemning a componentReport a problem with this question

2. 2. A controller's display and clock work normally and the programs are correct, but no station will operate, either automatically or by manual start. Which group of items should the technician suspect?

   • A.The station wire and splice for whichever zone was scheduled first
   • B.The common wire, transformer output, fuse, or master-valve relay✓ Answer
   • C.The diaphragm and seat inside each remote-control valve on site
   • D.The nozzle screens and filters in the heads throughout the system

   Scope of symptom points to the fault. When every zone fails at once, the failed element must be one that all zones share, and the shared elements are the 24 V supply, the fuse, the common wire and any master valve or pump relay in the path. A fault in one station's wire, splice or solenoid can only disable that one station.

   Source: Irrigation Association Certified Irrigation Technician content outline, Understanding Electrical Principles — controller electrical operation and diagnosticsReport a problem with this question

3. 3. A controller's display is blank. The technician measures 120 VAC across the transformer's input leads and 0 VAC across its output leads. What does this indicate?

   • A.The main breaker feeding the controller has tripped and cut all power
   • B.The station output triac is shorted and holding every zone energized
   • C.The field common wire has been cut somewhere between two valve boxes
   • D.The transformer has failed and must be replaced with one of matching rating✓ Answer

   Correct primary voltage with no secondary output means the transformer itself is not transferring power, so it is the failed component. The replacement must match the original in secondary voltage and in VA capacity, because an undersized unit will overheat when several solenoids and a master valve are energized together.

   Source: Irrigation Association, Electrical Troubleshooting Student Workbook — testing transformer incoming and outgoing voltageReport a problem with this question

4. 4. Every time station 6 starts, the controller's fuse blows. With a new fuse installed and station 6 skipped, all other stations run for days without trouble. What is the MOST likely cause?

   • A.An undersized transformer that cannot carry six stations
   • B.A short in the field wiring or solenoid serving station 6✓ Answer
   • C.A defective controller memory chip that corrupts programs
   • D.A rain sensor stuck closed and grounding the shared common wire

   A fuse opens because current rose above its rating, and a repeat failure tied to one station means that station's circuit is drawing far more current than a healthy solenoid does. Running the stations one at a time after replacing the fuse is exactly how the faulted leg is identified, and here it has already pointed at station 6.

   Source: Irrigation Association, Electrical Troubleshooting Student Workbook — overcurrent protection and station-by-station isolation of field shortsReport a problem with this question

5. 5. With station 2 called, the technician reads 25 VAC between that station terminal and common at the controller, then opens the valve box and reads 0.3 VAC across the same solenoid's leads. Where is the fault?

   • A.In the solenoid coil, which has failed open on that valve
   • B.In the buried field wire between the controller and that valve✓ Answer
   • C.In the controller's output circuit serving that particular station
   • D.In the valve diaphragm, which has jammed hard against its seat

   The controller is delivering normal operating voltage, so the output stage and the program are sound; the voltage has been lost somewhere between the two test points. A break, a corroded splice or a severely undersized run all show this pattern, and a wire tracker is then used to follow the station wire to the point where the signal stops.

   Source: Irrigation Association, Electrical Troubleshooting Student Workbook — voltage testing at the controller terminal versus at the valveReport a problem with this question

6. 6. A zone does not run when the controller calls it. The technician opens that valve's manual bleed and the zone waters normally at full pressure. What does this observation establish?

   • A.The mainline is shut downstream, so the fault lies in the supply piping
   • B.The nozzles are plugged, so the zone cannot build working pressure
   • C.The supply and valve are sound, so the fault is on the electrical side✓ Answer
   • D.The diaphragm is torn, so the valve can no longer hold itself closed

   Opening the bleed vents the bonnet chamber mechanically, doing by hand what the solenoid would do electrically. Since the zone then waters at full pressure, water is reaching the valve and the valve body and diaphragm work, which leaves the 24 V path — station wire, splices, common or coil — as the only remaining suspect.

   Source: Irrigation Association, Irrigation System Installation and Maintenance — using the manual bleed to separate hydraulic from electrical faultsReport a problem with this question

7. 7. Whenever station 5 is activated, the valves for station 5 and station 8 both open. The wiring at the controller terminal strip is confirmed correct. What is the MOST likely cause?

   • A.The common wire is undersized for the combined load of both valves
   • B.The solenoid on station 8 has an internal short drawing extra current
   • C.The insulation is damaged and lets two station wires touch in a trench✓ Answer
   • D.The controller has lost its program memory and runs two start times

   Two station wires bared against each other, usually where they were nicked in a shared trench or crowded into one splice, put both solenoids in parallel across a single output, so energizing one terminal energizes both coils. Program faults change when zones run, not which valves open together on one call.

   Source: Irrigation Association, Electrical Troubleshooting Student Workbook — field wiring faults, damaged insulation and cross-connected stationsReport a problem with this question

8. 8. A zone runs on some days and not others; the solenoid and the controller both test good. Digging along the station wire, the technician uncovers a buried splice made with plastic wire nuts wrapped in electrical tape. What is the correct repair?

   • A.Solder the joint and coat it with an all-purpose petroleum grease
   • B.Retape the existing wire nuts with several more layers of vinyl tape
   • C.Redo the splice using waterproof direct-burial wire connectors✓ Answer
   • D.Move the splice up into the valve box and leave the wire nuts in place

   Tape and bare wire nuts admit moisture, and the corrosion that follows raises resistance until the coil no longer pulls in reliably, which is exactly the intermittent behavior described. Gel- or silicone-filled direct-burial connectors seal the conductors from soil moisture and are the accepted underground splice.

   Source: Irrigation Association, Irrigation System Installation and Maintenance — waterproof direct-burial connectors for underground low-voltage splicesReport a problem with this question

9. 9. One rotor on a zone throws only about half its usual radius, while the other rotors on that same zone look normal. What should the technician check FIRST?

   • A.The controller run time, which is too short for that station
   • B.The pressure regulator setting, which sits above design pressure
   • C.The filter screen and nozzle of that rotor, for grit and debris✓ Answer
   • D.The transformer output voltage, because low voltage weakens throw

   Only one head on the zone is affected, so anything shared by the zone — pressure, run time, the valve and the supply — cannot be the cause. A partly blocked screen or nozzle orifice restricts flow at that single head, and cleaning it costs minutes, so it is checked before the head is condemned and replaced.

   Source: Irrigation Association, Irrigation System Installation and Maintenance — sprinkler and nozzle maintenance, cleaning filter screensReport a problem with this question

10. 10. A zone keeps watering after the controller has been switched off and the station is confirmed de-energized. What is the MOST likely cause?

    • A.A piece of debris trapped between the diaphragm and its seat✓ Answer
    • B.A pressure regulator adjusted far above its design setting value
    • C.A controller start time that was entered twice by mistake
    • D.A solenoid coil that has burned open and lost continuity

    With no power on the station the valve must close by hydraulic means, and it can only do that if the diaphragm seals fully against the seat. A stone, a sliver of pipe shaving or grit holds the diaphragm off its seat and leaves a path open, so the zone keeps running until the valve is opened and the seat is cleaned.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — remote control valve troubleshootingReport a problem with this question

11. 11. In a normally closed diaphragm remote-control valve, what holds the valve shut while the zone is off?

    • A.Spring tension alone, independent of any water pressure
    • B.Magnetic force from the energized solenoid pressing the diaphragm
    • C.Vacuum created downstream as water drains from the lateral
    • D.Line pressure bled into the bonnet chamber above the diaphragm✓ Answer

    Line pressure passes through a small port into the chamber above the diaphragm, and because that chamber acts on a larger area than the inlet does, the net force pushes the diaphragm onto the seat. Energizing the solenoid vents that chamber, the pressure above drops, and inlet pressure lifts the diaphragm to open the valve.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — diaphragm valve operationReport a problem with this question

12. 12. Water runs out of the lowest sprinkler on a sloped zone for roughly two minutes after the zone shuts off, then stops on its own and stays dry until the next cycle. What does this indicate, and what is the correct fix?

    • A.A cracked lateral pipe; excavate the line and install a repair coupling
    • B.Excess system pressure; add a pressure regulator ahead of the zone
    • C.A leaking valve diaphragm; disassemble the valve and replace the disc
    • D.Low-head drainage; install check valves in the low heads on that lateral✓ Answer

    The tell is that the flow stops by itself: only the water standing in the lateral above that head can drain out, so the discharge ends when the pipe is empty. A valve that fails to seal has the whole pressurized mainline behind it and weeps continuously, which is why a self-limiting discharge is corrected with check valves rather than valve service.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — low-head drainage and check valve applicationReport a problem with this question

13. 13. A technician opens a hose bib near the point of connection with no zones running and records 62 psi. What has actually been measured?

    • A.Working pressure available at the farthest head on that zone
    • B.Static pressure, which excludes friction loss under flow✓ Answer
    • C.Velocity head, which converts into pressure only inside the pipe
    • D.Dynamic pressure at the sprinkler, measured while the zone runs

    Static pressure is read with no water moving, so no friction loss is being generated anywhere in the pipe, fittings or valves. Once a zone runs, friction and any elevation gain subtract from that figure, which is why dynamic pressure must be taken at the head with the zone operating before a pressure complaint can be diagnosed.

    Source: Irrigation Association, Basic Irrigation Hydraulics Student Workbook — static versus dynamic (working) pressureReport a problem with this question

14. 14. On a drip zone, emitters near the valve wet the soil normally, but emitters at the far end of a long lateral barely drip. The filter is clean and the regulator is delivering its rated outlet pressure. What is the MOST likely cause?

    • A.The emitters at the far end are pressure-compensating and the near ones are not
    • B.The controller run time is too short for the emitter flow rate installed
    • C.The zone is missing a pressure regulator and the tubing is over-pressurized
    • D.The lateral run exceeds the maximum length the tubing and emitter flow allow✓ Answer

    Friction loss accumulates along the tubing, so pressure falls steadily from the inlet to the far end; past the manufacturer's maximum run length the remaining pressure is too low to drive the last emitters at their rated flow. The pattern of good output near the valve and poor output at the end is the signature of that loss, since a plugged filter or failed regulator would starve the whole zone.

    Source: Irrigation Association, Irrigation Components: Residential/Small Commercial Systems Student Workbook — micro-irrigation maximum lateral length and pressure variationReport a problem with this question

15. 15. A flow sensor on the mainline reports roughly double the normal reading whenever zone 4 runs, and the heads on that zone throw short with weak patterns. What should the technician suspect FIRST?

    • A.A clogged filter screen ahead of the zone's first head
    • B.A partly closed isolation valve upstream of the zone valve
    • C.A broken lateral or a head sheared off somewhere on that zone✓ Answer
    • D.A sensor K-factor entered wrong during commissioning

    An unrestricted opening in the lateral discharges far more water than the nozzles were sized for, which is why measured flow climbs while pressure at the remaining heads collapses and their throw shortens. Restrictions such as a closed valve or a fouled screen produce the opposite signature: low flow together with poor performance.

    Source: Irrigation Association Certified Irrigation Technician content outline, Understanding Hydraulic Principles — flow testing and flow meter readingsReport a problem with this question

16. 16. With the controller off and no fixture running inside the house, the small low-flow leak-detector dial on the water meter keeps turning. What is the technician's best next step?

    • A.Close the irrigation isolation valve and watch the dial again✓ Answer
    • B.Report a mainline break to the utility for immediate repair
    • C.Replace the water meter, since its register is clearly faulty now
    • D.Run each zone in turn and record the meter reading for each

    A turning leak dial proves only that water is moving somewhere past the meter, which could be the house plumbing or the irrigation side. Closing the isolation valve splits the service into two halves: if the dial stops, the loss is on the irrigation mainline, and if it keeps turning, the leak is in the building.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — using the water meter to identify and isolate leaksReport a problem with this question

17. 17. A system built with polyethylene lateral pipe is being winterized with compressed air. Which statement about the air supply is correct?

    • A.Air pressure at the poly pipe must be held to 50 psi or below✓ Answer
    • B.Air pressure of 250 psi is safe because the line is empty
    • C.Air pressure should be raised to 120 psi to clear the longest runs
    • D.Air volume matters little as long as pressure stays high

    Polyethylene is the weaker of the common lateral materials under air, and the accepted ceiling for blowout on poly is 50 psi, well below what is allowed on PVC. It is the volume of air, measured in cfm, that carries the water out of the pipe; raising pressure instead of volume only risks splitting fittings and destroying gear drives.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — winterization by compressed-air blowout, pressure limits by pipe materialReport a problem with this question

18. 18. During a compressed-air blowout the technician has been running one zone, and water has stopped leaving the heads, which are now discharging only mist. What must be done next?

    • A.Shut the air off to that zone before the dry heads overheat✓ Answer
    • B.Open every remaining zone at once to finish the job faster
    • C.Raise compressor pressure until the last drops are pushed out
    • D.Keep air on that zone for ten more minutes to dry the pipe

    Water passing through a sprinkler carries away the heat that friction generates; once the pipe is empty, nothing cools the nozzle or the gear drive and the plastic can distort or melt within a minute or two. Zones are therefore blown one at a time, only until mist appears, and the air is then moved to the next zone.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — compressed-air blowout procedure and equipment protectionReport a problem with this question

19. 19. At spring startup the mainline is empty, the manual drains have been closed and the backflow assembly has been reinstalled. How should the main supply valve be opened?

    • A.Slowly, a fraction of a turn at a time, so the mainline fills gradually✓ Answer
    • B.Halfway, and left in that position as a permanent restrictor
    • C.Only after each zone valve has been opened by hand at the box
    • D.Fully and quickly, so that trapped air is driven out at the heads

    Filling an empty mainline fast lets a column of water accelerate down the pipe and slam to a stop against a closed valve, and that surge, or water hammer, is what cracks pipe, blows fittings apart and lifts heads off swing joints. Opening a fraction of a turn at a time keeps velocity low while the air is displaced.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — spring startup, slow pressurization of the mainlineReport a problem with this question

20. 20. A buried PVC lateral has been cut through by a shovel, and the trench is tight enough that the two pipe ends cannot be flexed apart to take a slip coupling. Which repair method is appropriate?

    • A.Wrap the break with a rubber sheet held under two stainless steel clamps
    • B.Cut in a barbed insert coupling secured with clamps at both ends
    • C.Force PVC cement into the crack and hold the pipe until it sets
    • D.Install a telescoping slip-fix repair coupling in the cut-out section✓ Answer

    A telescoping repair coupling extends after the damaged piece is cut out, so it can be solvent welded to both fixed ends without moving the pipe, giving a joint as strong as the pipe itself. Cement will not bridge a gap or bond to a wet surface, and barbed insert fittings belong to polyethylene, not to rigid PVC laterals.

    Source: Irrigation Association, Irrigation System Installation and Maintenance — repairing broken PVC laterals with telescoping repair couplingsReport a problem with this question

21. 21. The relief port of a reduced-pressure principle backflow assembly discharges water continuously while the irrigation system is idle. What is the correct response?

    • A.Have the assembly serviced and retested by a certified backflow tester✓ Answer
    • B.Plug the relief port so the discharge stops and no water is wasted
    • C.Ignore it, because relief discharge is normal on an idle assembly
    • D.Raise the assembly higher above grade so the relief stops opening

    The relief valve opens whenever the zone between the two checks loses its required pressure differential, so continuous discharge means a fouled or leaking check, or a supply pressure that keeps fluctuating. The discharge is the assembly protecting the potable supply, so it must never be plugged; the assembly is repaired and recertified by a licensed or certified tester under the governing local requirements.

    Source: USC Foundation for Cross-Connection Control and Hydraulic Research, Manual of Cross-Connection Control — reduced pressure principle assembly relief valve discharge; ASSE 1013Report a problem with this question

Practice questions based on the Irrigation Association's published Certified Irrigation Technician content — basic irrigation principles, basic electrical principles and basic hydraulics — together with standard irrigation installation, hydraulics and backflow-prevention references. This site is not affiliated with or endorsed by the Irrigation Association. Irrigation work is governed by local plumbing and irrigation codes, water-purveyor rules and licensing that vary by jurisdiction; backflow assemblies in particular must be selected, installed and tested to the rules in force where you work. Confirm current exam requirements with the Irrigation Association before testing. About IA certification →