GM-GMC: 1999 Yukon electronic 4x4, 4wd system, electrical wires

Question
I assume that the electronic switching to all wheel / 4 wheel drive is made through electrical wires to some location on the front axles. Question - what happens if one of those wires breaks. Would this de-activate the drive to that or all wheels. Would that connection then fail open (wheel disengaged) or closed (engaged).Would I receive a message. Just theoretical but would appreciate advice. Thanks - Bob

Answer
The auto parts listings show that you have an electrical transfer case motor.  I am not sure how the front axle is engaged, but the overall system is electrically controlled.
There also appears to be a switch, that installs in the front axle, that is likely connected to your 4WD indicator.

If so, a failure of the system to engage would result in no indication by the light.

My 1984 GMC K-2500 has a purely mechanical 4WD system.  I am not familiar with the newer vehicles because I have not worked on any of them.