4 all time don't work (4x4 problems) on 2000 Jeep Grand Cherokee

all4x4 is not working, when the back tires are spinning the front tires do nothing. The back drive works fine. when I put it in low 4 it works fine all tires spin. help me out it snowing Thanks

Asked by for the 2000 Jeep Grand Cherokee
the front tires will spin when needed the truck has to be moving on all four wheels, this all time system is allways ready to work when needed, in other words is partially engaged unless needed, try this, put the tranfer case in 4L and if the front tires do not spin then you have a problem with the tranfer case check Vac lines and electrical conector first. Good luck
I have a 2004 Overland doing the same think - Just noticed it now the weather is turning - Works fine in 4lo - but in 4hi ( it is the 4HIGH - 4LO SELECTER TYPE) The front will not engage. I haven't checked anything yet - I did notice the indicator light is not on when in 4hi