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« on: September 02, 2019, 08:39:19 PM »
Well, the ESS board is getting a signal that the limit switch is active on start-up. I doubt it's a random start-up state in the controller. If the limit switches are, in fact, series-connected then they must also be normally closed (and open when activated).
Hypothetically, if the switches have a bad contact (and a slightly resistive path to ground or Vcc), then that will allow the pin voltage to float and produce a seemingly random error. A loose (or resistive) switch connection would do the same thing.
You may also be getting electrical noise on start-up that feed into the switches. Check the machine ground connection.
Monitor the voltage on this pin. A DVM may work but will need an o-scope to see the transients though.