As others have said… this is standard operating procedure. Cdl switches on with low range gearing. You typically want both about 90% of the time anyways.
That being said it is so nice for the other 10% of the time when you don’t want the two things working at the same time. That’s why so many do the cdl switch and pin 7 mod. There is wiring already in place for a separate center dif button, it’s behind your center control buttons up by the rear windshield heater button. Just buy a switch, get access, plug it in, and that’s done. I believe this allows you to press cdl in 4H. Then you go to the panel behind the dead pedal, and remove the pin 7 wire. I believe that is what gives you full control of cdl on/off in any range.
I would put this on a very high priority list. It’s easy, a good project to get you started on working on the vehicle, and it’s super useful. My bro uses cdl in high range cause he can’t be bothered to switch out of 4H sometimes. I always click it off when approach a sharp and slow (yet safe) turn.
I lent my little bro the 80 one time, he had no experience and I probably isn’t coach him enough on engine braking. He rode the brakes climbing down Yosemite and lost brakes altogether. He knew enough to swap to 4L to help him get down the steep climb without running into the cars in front of him. I had swapped in the cdl switch and pin 7 mod not a week earlier. Thank for I did that little $50 upgrade saved me so much in trouble due to the binding they would have experienced.
Anyways, fun first project. Do it soon. Welcome to the club