DTC P1826: Pressure Sensor For 4WD Supply Short To Ground: General Description
WARNING: This page is about a different car, the 2021 Kia Seltos. However, it is still accessible from the selected car via links, so may be relevant.
The 4WD ECU gets current pressure from a pressure which is installed at the coupling. And it controls a motor pump in order to generate a target oil pressure which will be tranferring a torque into rear wheels.