Solenoid Partially Working

[Codeguy]

Sorry if this was covered in another post, but I wasn't able to find what I need.

Problem - valve does not open when instructed to by the controller.

Equipment
Rain bird valve/solenoid
Installed around 2017

Things I've done
1) Manually rotating the solenoid counter-clockwise will open the valve correctly.
2) Opening the breather will open the valve correctly.
3) Connecting 3 9-volt batteries in series directly to the solenoid wires (not wired to the system) will open the valve correctly.
4) Measure the voltage at the control box shows 24-ish volts.
5) Measuring the voltage at the common and trigger wire at the valve shows 24-ish volts.
6) Measuring the voltage at the common and trigger wires with the solenoid connected shows 24-ish and then drop down.
7) Two new solenoids do the same thing.

I figure it has to be a wiring issue of some kind, but that's the mystery part. Can anyone suggest some more options or things to try?

 

[Fitter30]

Need to know the brand and model to look at the wiring.

 

[Sponsor]

 

[WorthFlorida]

Disconnect the solenoids on one side and measure ohms. Reading can be between 20-60 ohms but most will read about 30 ohms. The voltage drops but by how much? Dropping to 18v's under load is quite acceptable. All new Rainbird controllers can detect shorts with an error so the solenoids should be good.

How many zones in use? Move the troubled zone wire to a spare zone in the controller and give that a try.

Since two are giving you the problem and there are no other zones. I'm first suspecting a bad common wire connection. Most installations the zone wires and common are buried in the same trench and the common wire is daisy chained with each solenoid the common wires are connected with a wire nut. If you have three zones and one works, the working valve could be the first one in line.

Always possible the common wire was cut if any digging was performed in the yard recently.

 

[Codeguy]

Thanks for the input!

The solenoid is a model SRKCP/CPF.

The resistance of all the solenoids is about the same in the high 30's.

I hooked up my voltmeter, enabled the zone and it goes from almost nothing to 25/28 and then within a couple of second down to 3 or so. Way lower than 18.

I have 5 zones, the controller supports 6. All the other zones work fine. I moved the wire from the non-working zone to the unused zone and saw no change.

As for common's, the "middle" zone has 5 or six wires all tied together and then I'm assuming that splits to each of the valves. I confirmed continuity between the wire in the bad zone and the grouped up common. I agree that it does sound like some kind of bad wiring issue. Unfortunately, nothing was happening around the wiring any time recently, but of course one never knows.

So do you think the best plan would be to dig everything up and follow the wire and/or replace either or both the common or lead going to the non-working valve? Do you think there's any value in wiring the non-working zone to one of the working zones (on the solenoid side)?

Appreciate the thoughts!

 

[WorthFlorida]

Strange. An easy thing to try is swap out a known good solenoid with the bad zone, or, if you have wire just run it along the ground, any size wire to prove the problem. Or just pick up a new solenoid, $10-$12 usually. After the swap and the problem persist, sure seems to be a wire problem. Possibly something chewed on it. At night possums or raccoons like to dig for grubs.

Another thing to try is disconnect both wires at one solenoid and from the controller, then measure the resistance. it should be an open. Then try it as a short at the solenoid wires.

I know you moved the bad zone to an unused zone. Do you have a separate module for zone 5&6 as compared to zones 1-4?

 

[Codeguy]

Ok, additional information. The value in question has more than one wire in its circuit. This is due to the connected SMRT-Y Soil Moisture Sensor. I double checked and it appears to be wired the correct way. Could it be that the sensor has crapped out? If so, would that make only a single zone not work? Should I re-wire the timer to remove it from the circuit? Is there an easier way to bypass it?

Installation wiring diagram is here - https://manualzz.com/doc/1865504/rain-bird-smrt-y-soil-moisture-sensor-wiring-diagram

Also tested solenoid wired to a different zone and it worked just fine.

 

[WorthFlorida]

I'm not familiar with the SMRT-y and sensor and its difficult to read the manual with all of the ads popping up and small print. It does indicate it is for one zone only but I cannot under stand the override function connected to other zones other than a manual watering without having to turn on the controller using city water. Essential when the sensor activates it opens the 24v ac to the solenoid and that is what is happening. I would rewire this device out of it.

I have a few spots that never seems to get enough water because it dries out faster than other areas. I adjust the program for this and each of my four zones run on different watering durations.