Have you disconnected the TCCM/Dash-switch connections & inspected them for corrosion? If not, try that first. Faulty connections can cause false resistance readings to the TCCM making it think that a button on the switch is pressed when it is not.
Have you tested the switch resistances at both the switch itself and the connector at the TCCM? Again, if the resistances are off, the TCCM could sense a button push when it actually isn't being pressed.
Most phantom NV236 transfer case shifts are due to a fault in the dash switch to transfer case wiring