DTC P1810: Neutral-4LO Switch: Description
WARNING: This page is about a different car, the 2013 Nissan Armada. However, it is still accessible from the selected car via links, so may be relevant.
The neutral-4LO switch detects that the transfer case is in neutral or 4LO range. DTC P1810 will set when an improper signal from the neutral-4LO switch is input due to an open or short circuit.