The ABS is not part of the 4WD system so that is not going to cause this issue.
This system is pretty simple at this point, so we need to find out what the voltage is going to and returning from the switch.
So, you should have 12 volts going to the switch on the dark blue wire and then a reduced voltage returning on the same color wire depending on which setting you have selected.
Here is a guide that will help with this:
https://www.2carpros.com/articles/how-to-check-wiring
If this appears correct, then the likely cause is the four-wheel drive module.
However, we need to check the voltage from the DTCM to the transfer case assembly.
Please see the wiring diagram below and we can go from there.
Let me know what questions you have. Thanks
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Monday, March 7th, 2022 AT 8:42 AM