98 Suburban need help with P1875

New here. I search around but did not find an answer. I have a 98 Sub 5.7 4WD automatic (4L60E I think). It has 205K miles on it and I've owned it for 13yrs now. I do most of the maintenance my self. Recently new spider injection, fuel pump, fuel filter, plugs, cap, rotor and plug wires.
It currently has a DTC P1875. Any help and advice on how to fix it myself would be great. Thanks

P1875=4WD Low Switch Circuit Electrical. There are 9 steps for trouble shooting this DTC. Checking the GRY/BLK wire from the t-case to the VCM for open or short, replacing the t-case switch and/or the VCM.

What other indications do you have? CEL-4WD? When was the last time you were in 4LO? Might try cycling thru that a couple of times.