Here is a problem I've been having after spending some time in 4WD Lo, climbing a hill for a while. There is a whining noise from the transmission or transfer case, and it progressively gets louder. Eventually the front left wheel will stop turning due to the caliper sticking, and when I check it, it's REALLY hot. After cooling down for a while it unseizes and can drive again. In 4WD Hi the whining noise is much quieter and I haven't had it get to the point where the wheel seizes. In 2WD there is no whining noise at all.

Today I had the wheel seize twice in a mile while climbing a steep trail, and I eventually just pulled the caliper off the rotor so I could drive the ~3 miles back to the trailhead with no brakes. I then reinstalled the caliper and it was fine for the ~30 mile drive home (in 2WD, with no steep hill climbing.)

 

Any ideas what the problem could be?

The Hill-Holder (H-H) isn't releasing the brakes fully.

 

It's plumbed into the Left Front/Right Rear brake lines.

Ahh, that sounds like it could be the issue. Reading about the hill holder, it seems it's sensitive to the angle of the car? I recently installed a lift, front end only.