7 of 10 zones quit working

Last tested my Rachio 3 12-zone (Costco) 4 days ago to check coverage and replace broken nozzles. System was 100%. With the heat this week, I started noticing several zones looking dry. When tonight’s schedule started, I monitored it. The app shows every zone running normally, but only 3 zones are actually turning on. I can manually turn on the non-functioning zones at the valve by opening the bleed. I checked voltages at the controller, and this is what I get:

Functional zones: ~28 VAC when the zone is on, ~0 VAC when the zone is off.
Non-functional zones: ~27 VAC when the zone is on, ~5 VAC when two of the functioning zones are on, ~12 VAC when the third zone is on, and ~ 2.3 VAC when all zones are off.

The three zones that are functional have valves that are located within 10-20 feet of each other along one side of my house. Four non-functional zones are in the back yard, within 10-20 feet of each other. The other three non-functional zones are in the front yard opposite the master valve. I’m providing this information because my fear is that this may be a broken ground. I think I’d rather have my controller go bad than try to chase ground wires that I have no idea where they’re buried.

Where do I start?

The 5 VAC when off seems odd. If you disconnect the wire, do you still see the voltage when off and does it change the on voltage?

I probably would also try the following as the next couple of tests:

  1. Check the voltages at the valves
  2. Try switching the wires of a non-functioning zone with a functioning zone

Any power surges that you know of? Any digging where the wires might be? Is it possible the the wires were bumped and the wire nuts came loose enough to not make a good connection with the valve wires?


Thomas, I just edited my post, so please check the changes I made to the voltages. But I did not disconnect the wires, I just stuck my probe into small exposed area. We did have a brief power outage, and now that I think about it, it was the night after I tested the system. No digging Wires are solid at the controller. It would make sense that maybe the ground wire feeds through the 3 good zones and has become disconnected between that 3rd zone and the 4th zone which is the first of the 7 bad zones, because that is physically how they go around the house. I’ll first check the 3rd and 4th zone boxes. If that doesn’t pan out, I’ll check voltages at the valves.

Wires all look solid at the 3rd and 4th valve boxes. When I open the bleed on the 4th box, water started to flow, but then stopped. Checked the 5th and 6th boxes, wires looked good, but when I opened their bleeds, nothing. Swapped leads at the controller between two zones, one functioning and one non-functioning. The functioning zone still functions when I turn on the non-functioning zone, and the non-functioning zone still doesn’t work when I turn on the functioning zone. That would rule out the controller.

One more update before I head out for the day: with daylight, I was able to turn on the first non-functioning zone in line by turning the solenoid 1/4 turn, as well as the next zone, but none of the following 5 zones will come on by turning the solenoid, even though last night some of them came on when I opened the bleed. Probably something I don’t understand about irrigation valves…

Out of time for the day, but will continue looking this evening and over the weekend. Really appreciate any help anyone can offer, since this will be my primary task this weekend, and irrigation systems confound me.

Do you have a master valve? Backflow? Isolation valves? I would definitely check all of the wire connections at the valve locations make sure you have waterproof connectors.

It sounds like a possible issue on the common side. Any pics of the Rachio wiring and maybe a map of what’s going on in the yard would help w/ the trouble shooting.


@gaustin has some good questions and comments. I cannot think of anything else off hand at the moment.

Sounds like you have an issue with your valves rather than the rachio.
this is a decent guide for troubleshooting cables and solenoids:


Thanks to ParB for the troubleshooting guide. It got me to structure my troubleshooting a little more, and in doing so, to really think about how my irrigation system was wired together. Although I built this house, half of the irrigation system was installed by the builder, and the other half was done after we put in our pool, which happened just after the house was built. So I now realize that the system is laid out electrically thus: Zone 10, 4, 5, 6, 7, 8, 1, 2, 3. Zones 10, 4, and 5 worked and the rest didn’t. I figured it had to be a loose ground connection somewhere past zone 5, because everything else had basically infinity resistance when doing the continuity checks. But connections were fine in both zone 5 & 6 boxes. So I took a chance and dug out the only coil of wire I have on hand, 10 gauge stranded copper, and took the wire nuts off the ground wire bundles at zones 5 & 6, and wired in the 10 gauge, just laying it above ground to connect the two zones. Bingo, problem solved. All zones are working, and I’m getting much-needed water to my brown lawn. Although I know 10 gauge stranded is WAY overkill for this application, but it’s only a 30 foot stretch, and I’ve already cut the wire from the spool. Is there any reason why I shouldn’t just bury this wire and be done with it? It would be in a mulched area following a stone border, do little likelihood of inadvertent damage due to digging (especially since I know it’s there).

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@dws3 - I’d vote for burying it. Before that I’d hook up the common wire in zone 5 and 6 one last time to see if there was some corrosion that was knocked off by undoing the wire nuts or use the 10 gauge strand as one leg and see if the common wire between zone 5 and 6 is good (i.e. connect the 10 gauge wire to the common wire going from zone 6 to 5 and test the ends at zone 5. Seems strange that one wire would go bad. I’m assuming that the field wire is the common and all the zone wires with a jacket over them and not individual wires.

Water wire nuts are be used for the connections - right?

We are glad you found a solution to the problem to get some water down.

@DLane, I twisted the 10 gauge wire right in there with the existing two ground wires using a regular wire nut, but when I bury it, I will use waterproof wire nuts. The existing twisted joints are still immersed in dielectric paste, so I didn’t even try to separate them, nor do I intend to, since it’s difficult to determine which wire is coming in and which wire is going out, as they are pretty well buried. It might not hurt to put things back the way they were one last time and see if it works again. I’m not sure why a wire would break unless someone cut through it, which I am positive didn’t happen in this case.
But the troubleshooting guide I followed insisted that if the continuity was bad, “dig up the wire and replace it”. I say to heck with that, leave the old wire there and run another one! Not sure what you mean by “field wire”, but I have individual wires running from my controller to each valve. The common goes from the controller to zone 10, then to 4, 5, 6, 7, 8, 9, 1, 2 and 3. Or at least that’s what I assume, based on valve location and my memory of how the system was installed


Field wire, multiple wires in one casing, e.g. ->


Leave zone 6 connected, but split out the wires at zone 5. Test each of the old wires with the 10 gauge as the return. If both test infinite resistance then there is a break. If one is low resistance, then that one is going to zone 6 and the other one is going back to the controller. Just curious.

@dws3, the common wire could have had a nick in the insulation during install and it just took this long to corrode and ground out. I’ve seen all kinds of crazy things, just take your yard and multiply it up to 100 acre golf course with wire running for miles(in lightning country). Glad you got the system running.

Fun stuff… I can’t imagine anything more annoying than ghosts in the electrical return (zero). I worked during my college years as a sound engineer, boring both studios as well as doing audio for sports events. Chasing noise in returns was never fun, and your problem isn’t that different from that.

I’d say go overkill. Its for sure what I would have done!