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How to replace a controller / timer

If you already have a controller that is giving you problems and find that you need to replace it with a new one, let me reassure you that it is very easy to replace an irrigation system controller and most any homeowner or irrigation repair person can handle this task.

Before beginning the replacement, first determine if this procedure is really necessary.  Your problem may be the result of a blown fuse or a transformer failure.  If the controller has no power, proceed with the controller replacement.


1Write down all existing programming on the old controller. Include notes on which days to water, what time to start watering, and how long for each zone.

 If the old irrigationcontroller is completely dead and you can not get this information, no worries, as you can program the new controller to water a few days a week and the rotor zones for 20 minutes and the spray head zones for 5 to 8 minutes each time they come on. A good start time is 4:00 or 5:00 am so that all the watering is completed before you need to start using water in the house in the morning. Then you can adjust these settings later as you find that the yard is getting watered too much or not enough.


1Unplug the transformer from the wall or turn off the power to the controller at the breaker box. Do NOT go any further until you are absolutely certain that there is NO electrical power to the controller.

1Remove the face of the controller

1Disconnect the field wires and label each one with a piece of masking tape as you remove them. Use the following method to label the wires:

      • The two most important wires to pay attention to are the COMMON and (if your system is run by a pump without a pressure tank) the PUMP START WIRE.
      • The common terminal in the controller is usually marked by the letter “C”.
      • The pump start terminal will be labeled either “PS” or “MV”.

1 1

1Replace your controller with the same model and brand as you already have on your system. If you can not buy the same model, that’s ok, just get one that has the correct number of stations or zones that you had on your old timer and make sure you get all the features you want.

1Frequently, all of the field wires will be a different color. Simply write down which color wire relates to which terminal. (e.g. white=common, Red=Zone 1, Green=Zone 2, etc.)

1Unscrew the old controller from the wall and mount the new one.

1Re-connect the power wires and turn on the breaker or plug in the transformer.

1Connect your zone field wires and test that ever zone comes on.

1Now your new controller should be fully functional and ready for programming. Referring to your programming notes from step 1, program your new controller.



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