2 zones coming on at once

I have a 16 zone system with 14 active zones (Rachio model 16ZULW-B). Two of the zones (zones 1 & 5) are coming on at the same time. All other zones work as expected. The firmware for the Rachio is at the latest release. If I start zone 1 directly from the Rachio controller zone 5 also starts and likewise, when I start zone 5 directly from the controller zone 1 also turns on. I replaced the solenoids on both zones but the issue continues. The valves for zone 1 and zone 5 are in two different valve boxes in my yard (about 30 yards apart). If I disconnect the zone 5 wire from the controller and start zone 1, the sprinklers on zone 5 will still come on. Likewise if I disconnect the zone 1 wire (having reconnected zone 5) and then run zone 5, the sprinklers for zone 1 will still come on.
When I operate zone 1 and zone 5 directly from the valve each operates as expected (without the other coming on).
The sprinkler system has been working fine for the past 18 months (when I changed over to the Rachio controller). I have not added or removed anything from the sprinkler system configuration over the past 18 months.
Any thoughts and suggestions on how I might troubleshoot and resolve this issue. Any help is appreciated.

Sounds like the wires are shorted somewhere. Possibly damaged during initial install and shifted to short during Rachio upgrade. Any chance you have a spare wire in your cable bundle? If you get a multimeter, you could verify if your zones are really shorted, but what else could it be?

1 Like

Gene - Thanks for your reply.

Unfortunately there are no spare wires in the cable bundle.
I did test resistance on all 14 zones (disconnected power to Rachio prior to testing). All 14 zones came back with readings between 26 and 39 ohms. From what I have read those readings are all within the acceptable range (which I have read is between 20 and 60).
If you have any additional suggestions I’m certainly ready to give them a try.

@BoulderSkies - first off great job on the initial troubleshooting. I’m going to agree with @Gene, in that somewhere the zone 1 and zone 5 wires are joined together.

From the initial testing:

  1. The piping error domain was removed when the zones watered properly when manually activated at the valves.
  2. The Rachio error domain was removed when each zone was removed from its terminal in the Rachio and it still activated with the other zone when the other zone was selected on the Rachio.

I’m not sure the multimeter test would have found anything. It will report the least amount of resistivity in the line, which is one solenoid. We know neither line is open as both lines operate the valves independently in the Rachio.

I’d recommend checking the wiring connections in both valve boxes for those two zones/valves. Posting pictures of the Rachio wiring and the connections in the two valve boxes might give Gene and I other ideas.

And welcome to the community.


Multimeter test I had in mind did not involve measuring impedance on each zone relative to the commons, rather you would want to test impedance between zones 1 and 5. Normally impedance should show 2x average zone value as you would be measuring two solenoids in series, what I expect is a reading that is much lower than any other zone.
Also, in case you are using similar solenoids throughout, reading of 26 ohms suggests that you are measuring two solenoids in parallel as it is roughly half of the maximum impedance of 39 Ohms.
I’m with @DLane’s suggesting to carefully inspect wiring and take as many pictures as you can. Your testing methods pretty much eliminated an issue at the controller and the valves, problem is somewhere between those two things.

Please measure the following combinations with Rachio disconnected
Zone 1 to Zone 3, Zone 1 to Zone 5, Zone 3 to Zone 5.
Let us know the results. Thank you


It appears to be a wiring problem, so the question is how to isolate the problem between your Zones 1 & 5. I do irrigation as a small business and have encountered a prospective customer with a 13 Zone Rachio Controller that is running two stations at the same time. I think that in his frustration he ordered a new Hunter controller to which I advised him not to install it until he solves the 2-station problem. So, this is what I would do. 1. First, determine if it is in fact a wiring problem. 2. Go to the place where all the wires are bundled and fished into your garage where your controller is located. 3. Isolate Zone 5 and cut the station wire. You will need a Pro-48 to isolate which wire it is if the are all the same color. Then test your Controller. If both Zone 1 and 5 activate, then your problem is a wire problem shared by Zone 1 to Zone 5. If Zone 1 is the only one operating then it is Zone 5 that shares wire with Zone 1. To confirm this, reconnect your Zone 5 and cut the Zone 1 station hot wire outside at point of entry (you will need a Pro-48 to isolate the wire); run your zone 5; if only Zone 5 activates, then Zone 5 wire is not shared with Zone 1. Go to work and and find where those wires are being shared. The alternative is to splice a new wire Zone 1 entry point to house and run it all the way to Zone 1 valve box and wire to solenoid; cut the original wire. Just my thoughts on troubleshooting the problem. I plan to meet with him next week; he also has a pump, I can tell he is very frustrated. I will report my findings at a future note. Stay safe out there. Roy

I have used an ohm meter that give me 10 ohms on one station that does not work. My Pro-48 indicates the solenoid to be “Good”. But what that tells me is that the solenoid is marginal and will not work. I have a customer with that problem; I’ve ordered a new valve to fix the problem. Might as well gut the old one out while I’m there and give him new solenoid and diaphragm to go with it. Will see what happens.