Center Differential Lock Detection Switch (Montero)
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 1994 Mitsubishi Montero, 1993 Mitsubishi Montero, 1993 Dodge Ram 50, 1992 Mitsubishi Pickup, and 1992 Mitsubishi Montero. However, it is still accessible from the selected car via links, so may be relevant.
Check continuity between terminals at Brown wire connector terminal on side of transfer case. With transfer control lever in "4H" position, there should be no continuity. With transfer control lever in "4HLc" position, there should be continuity. See Figure.