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Q. I have a valve that won’t stop running. Is it the controller?

A. Probably not. 99% of the time when a valve won’t shut off it is not the controller nor is it an electrical problem. Try taking the valve apart and look for rocks or debris or a damaged diaphragm.

Q. What is the normal voltage output for an irrigation controller?

A. Normally 24 volts AC, but it can vary based on the high voltage input to the controller.

Q. Sometimes my controller puts out 24 volts on all of the terminal posts even if it is not running. Why?

A. Your controller is not broken. Sometimes a controller will put out “phantom” voltage on terminal outputs that have no valve wired up to them. This is normal for some controllers.

Q. Do I use an Ohm meter reading to diagnose a problem?

A. Ohm readings are the most accurate and reliable way to diagnose field wiring, not a volt reading. Disconnect the common wire from the terminal strip and leave the hot wires hooked up. Set your meter to Ohms. Next touch the red lead to the terminal strip on the valve wire in question and the common to the disconnected common wire. Check your reading. You should have one of the following readings:

Q. I think I have a short on a field wire. How can I be sure?

A. First, you need to make sure it is a “short”. There are three things that can go wrong with field wiring:

Q. How can I be sure my controller is working properly?

A. Follow these steps:

  1. Check to make sure there is a display and that there appears to be power.
  2. Check the programming to make sure there is a start time, runtime and watering days selected for the zones in question.
  3. Make sure the water percent adjust key is not set to zero (by program and globally).
  4. Make sure the rain switch is not activated.
  5. Using a volt meter, set it to AC voltage and check each station by turning it on manually and touch the leads to the common post and the hot wire for the valve in question. You should read 24 volts. As a double check take a valve solenoid with a captured solenoid and touch it off to the same hot a common wires. It should “click” audibly.
  6. If all these check out, your controller is fine.

Q. I have a wire checker that just has lights and sound, not actual readings. Will this work for diagnosing wiring problems?

A. Initially as a quick check, yes, but for accurate and reliable wire troubleshooting you will need to get a digital volt-ohm meter and learn how to use it.

Q. I think my building wiring is messed up where my controller plugs in. How can I check it?

A. Get a plug-in wiring tester and plug it in. It will tell you if the ground is good and if the hot and common are reversed.

Q. What type of meter is best for troubleshooting irrigation wiring problems?

A. Keep it simple, simple, simple. 95% of all irrigation field wiring problems can be diagnosed with AC voltage readings and Ohms readings. All the other bells and whistles on big, expensive, fancy meters will never be used. In addition, those big complicated meters are hard to use as well. They also set the stage for bad readings if you do not use them correctly.

Q. What types of tools are most useful for diagnosing irrigation wiring problems?

A. Besides a digital Volt – Ohm meter it is useful to have an analog meter for checking DC systems. Also, an inductive amplifier will save lots of time in sorting out wires and doing basic tracking. Finally, a good wire tracking device will be indispensable in tracking down wire paths, buried valves and broken wires.

Q. I have two valves wired together out in the field. Will this change my Ohm readings?

A. Yes, it will cut your Ohm readings in half. For example, if one valve Ohms out at 30 Ohms then two valves will Ohm out at 15 Ohms (from the controller).

Q. I find myself walking all over the job site trying to figure out wiring problems and many times I just run a new wire to fix it. Is there a better way?

A. Yes, there is a specific sequence to troubleshooting. If you follow that sequence each and every time, your troubleshooting will go much smoother and quicker and you will not have to run new wire. In general, you should always do the following in order:

  1. Check the controller
  2. Field wiring
  3. Solenoids

The best place to learn that sequence in detail is in the book, “Troubleshooting Irrigation Control Systems” and the “Electrical Troubleshooting Training” DVD.

Almost all of your diagnosis should be done from the controller, not from the field. From the controller you can, of course, check out the controller, but you can also check out the field wire and solenoid. Use your volt meter to check out the controller and your Ohm meter to check out the field wire and solenoids. Even though your leads are technically in the controller when you are doing an Ohm check, when you touch them to the terminal strip with field wires hooked up, you are not checking out the controller, you are checking out the field wires and solenoid.

Q. What is an Ohm reading and how does it work?

A. Ohms are a unit of measurement for resistance. It measures how much resistance there is in the wire to the free flow of electricity in a circuit. It is your most valuable tool for troubleshooting field wiring problems.

Q. How much resistance is there in the field wire of a typical irrigation valve circuit? How much in the solenoid itself?

A. In a complete valve circuit there is about 20-60 Ohms of resistance (depending on the brand of solenoid). Of that, almost all of the resistance is in the solenoid. Only about 2-3 Ohms are lost in the wire itself.