All of a sudden, a handful of insteon lights switch on by programming, but then switch off spontaneously in a second. Have checked all programming and nothing has changed. Have tried reboot but problem persists. Any ideas?

Handful? Like a scene maybe? Always the same ones?

Almost all (about 12)

None are in scenes.

Same thing happened to me a couple of months ago. No record in the logs.

I did a power cycle on the eisy and also did a link table diagnosis/compare on all the affected devices. Did a restore device on any mismatched link tables. All is good now.

Also take a look at all your programs to make sure you don't have a corrupted command(s)

@SHM , since you are not using scenes, I am guessing that you are turning on multiple individual devices in a single program. That can cause issues where the PLM is bombarded by serial commands thereby causing errors. These errors can lead to uncommanded On/Off, PLM reset, etc. An example is shown in the link below.

plm-problem-uncommanded-on-for-multiple-devices

Not all devices are susceptible to the uncommanded On/Off. Newer Insteon devices have had the command removed. Fortunately, you can test if your devices are susceptible. Please not that the following will turn on/off ALL susceptible devices in your house. Not something to take lightly if you have motors/fans/garage doors/etc. controlled by Insteon. It will also issue commands to X10 devices (and possibly Z-Wave and Zigbee).

I normally use an OFF command since it is less intrusive (try to run when other family members are away or asleep) -

• Manually turn ON devices you wish to test.

• Open your event viewer and place on Level 3

• From the Admin Console tree - Select "My Lighting".

• From the My Lighting device window - Select "All Off"

In the event viewer you should see the following I1 command from the Eisy to the PLM, and the PLM ACK.

Devices that turn OFF have not had the command removed and are susceptible.

Sat 10/31/2026 08:25:12 AM : [INST-TX-I1  ] 02 62 00 00 FF CF 14 00
Sat 10/31/2026 08:25:12 AM : [INST-ACK    ] 02 62 00.00.FF CF 14 00 06          LTOFF-F(00)

If you determine that your device are susceptible you have a few "preventative" measures you can take:

1. Review the Wiki for program activation recommendations - INSTEON_Random_All_On_Events

2. Insert wait commands between successive Insteon commands to prevent overloading the PLM

3. If you have good communications, use scenes to turn your devices on/off.

Thanks