3-way behaves incorrectly depending on dumb switch state

I’m in the process of installing a number of my blue 2-in-1s (VZM31-SN) and one of my 3-ways is behaving oddly depending on the position of the dumb switch. When the dumb switch is in the down position, the smart switch behaves as I would expect when toggling it or flipping it through Home Assistant ZHA. However:

  1. When Smart is on, I flip dumb up, smart turns off for a second and then turns back on again
  2. After this if I flip dumb down again, nothing will happen, smart and lights stays on
  3. I flip dumb up again, smart will again turn off for a second and then the relay/LED clicks on again.
  4. I can rinse and repeat this loop, to break it I have to put dumb down and only toggle smart

Some other facts:

  • This was a functioning 3-way dumb switch before I started.
  • I have a neutral and line attached to the smart switch
  • The load is 4 outdoor scones with built in LEDs, each fixture has an integrated dusk-to-dawn photo sensor
  • The switch is running firmware 1.12
  • In Home Assistant ZHA I’ve verified that I have the switch configured for On/Off mode and 3-way dumb
  • The dumb switch is in the two gang box, it’s hard to see but all 3 conductors do directly to a single 14-3 leaving the box, they are not pigtailed to anything in the box
  • The smart switch in question is the middle switch in the 4-gang box

Is this a wiring issue? Otherwise, I wonder if there’s an issue with how the dusk-dawn LED lights behave as a load? Could replacing the dumb switch with an Aux switch improve the situation?

Didn’t look at your wiring, but I have a sneaking suspicion that you may be correct regarding the dusk to dawn sensors. I would test first to eliminate that.

Remove the load and temporarily wire in a pigtail light socket with a bulb. See if it works normally with that.

When on and you flip the dumb down do you hear the relay in the smart switch click? Because if you don’t then its wired wrong. The only way for power to get to the opposite traveler wire and keep powering the load when you switch the dumb switch is by the smart switch switching the relay.

@PJF to your question, no I don’t hear the relay click.

@Bry the behavior is the same but I’m also not sure I completed your test correctly. Did I miss something here with the light socket setup?

I am on my phone and it’s a little tough to see in the sun. You should have removed the black load conductor from the Inovelli and substituted the black line conductor from the light bulb. If that is what you did then you did what I was suggesting.

@PJF brings up a good point about hearing the relay click. You wired this as a load between the switches, right? Did you confirm the black wire at the Inovelli is actually the load? You should have first made sure there was not 120VAC one that black, and then if that was the case, jumpered 120 VAC to see that turned the light on.

When this was a dumb switch setup, did the line originate in the box that you are now putting the Inovelli in?

While there are no absolute rules when it comes to which conductor goes to which terminal, I would expect that both black screws on the dumb switches would have black conductors. In your picture of the dumb switch, I think, there is a white conductor attached to the black screw. (Again, I am on my phone in the sun so correct me if I am wrong.)

If that is the case and you just simply followed the Inovelli wiring diagram, then that diagram may not be absolutely correct.

If you can get at the first light box and can examine the connections of the two three wires and the conductor feeding the load, then that might be helpful.

Otherwise, I suppose it’s possible it is a setting issue. I know that you said that you set settings correctly but perhaps we should double check. I have a low tolerance for pain so I do not use HA any more than I have to. So @pjf can help you with that.

The wiring looks correct but it’s hard to tell. The 3 wires at the dumb switch look like white is the common because it hooks to the black screw. The red and black are travelers so they go to the load and traveler or red screw on the Inovelli. The white wire returning in the 3 wire bundle goes to the load hot in the Inovelli box. The load neutral goes to the neutral bundle. The Inovelli gets hot and neutral from the bundles in the box.

To do that test you need to hook that bulb to the white wire returning in that 3-wire bundle.