How to Repair a Soil Moisture Sensor How to Repair a Soil Moisture Sensor

What You'll Need
Soil moisture senor kit
Electrical tape
Flat shovel
Wiring Soil

There are are some common problems that can occur after you've installed your soil moisture sensor. In heavier soils, soil shrinkage can cause the reading on the device to be exceptionally high, as the sensor is not getting fully re-wet. In this case, a full re-wetting of the soil and sensor can usually rectify the problem. However, if your sensor is not fitting snugly in the soil or if irrigation is not reaching the sensor area, there may be a rock or some other sort of impediment to the water movement, in which case reinstalling the sensor will probably get things running smoothly again. Before you get started with the re-installation, manually turn on the zone where the sensor is to be installed and the adjacent zones. Observe the water distribution patterns and select the sensor installation spot.

Step 1 - Turn the Sprinklers "On"

Turn on the sprinkler zone where the sensor is installed as well as all of the adjacent zones.  Ensure that the sensor is in a placement where there is healthy turf and the subsoil has proper drainage.

Step 2 - Locate the Valve Box

Find the closest valve box to where the sensor is and locate both ends of the valve box wire which is in the zone as well as the controller box.  Place electrical tape on the zone wire connected to that valve and then put a piece of the tape on the other end of the controller box wire.  Be careful that you are selecting the zone wire instead of the common wire.

Step 3 - Dig Your Holes

With a flat shovel, make 3 sides of an 18 by 18 inch square which is 6 inches deep. This should create a "U" shape. Dig under the sod, and pull it back about 4 inches, leaving the soil exposed to about 3 to 4 inches deep. Right next to that area, about 6 inches away, dig a similar opening than can fit about a 7 inch valve box. The valve box, when placed, will be used to splice the wiring from the zone wire you've identified in the previous step to the sensor.

Step 4 - Make a Trench

Dig out a narrow trench going from the 7 inch valve box location over to the bottom of the 18 by 18 square that you made for the sensor.

Step 5 - Position the Sensor

Position the sensor horizontally into the bottom of the 18 by18 "U" shaped hole that you dug. Keep the wires of the sensor going along the direction of the trench which leads back to the wiring box. Pack the soil securely around the sensor rods down to about 1/2 inch. Finally, roll the sod back over the sensor and firmly pack it.

Step 6 - Connect the Wires

Inside the wiring box, connect the wires of the sensor to the cable that goes to the valve box. After ensuring the correct operation, make use of grease caps on all connections.

Step 7 - Check the Connections

Disconnect the zone wire that you previously marked from the valve and then take the extension cable that had been connected to the red sensor wire and connect it. This should be the only wire attached to this connection. Take the disconnected valve and reconnect it back to the sensor wire with the black extension.  Connect the sensor wire with the white extension to the common valve box wire. Take care to ensure that the valves all have the same connection with the white sensor wire.

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