2000 GMC Jimmy 4wd engages by itself

[ajbrannigan04]

My 2000 GMC Jimmy locks into 4 wheel high after driving for long periods. The switch on the dash shows it is in 2 wheel but the motor makes a loud grinding noise. When you switch it into 4 wheel high the grinding noise stops. After playing back and forth with the switch (pressing 2 wheel and then 4 wheel if it makes the noise and back and forth) it eventually locks back into 2 wheel. I have tried unhooking the switch but it still does it. I need to know what is bad to fix this issue cause it is driving me crazy. If anyone has any ideas please let me know.

[jaredlucky16]

FOr the mean time unplug the actuator on the front diff