When driving on the slippery roads in chicago here when i come to a stop and and its all snow when i hit the gas it kinda slams in to 4x4 which is normal i know. but it keeps going in and out its like a knock noise with the axles or something but when i put it manually into 4x4 everythings fine on dry pavement everythings fine just when the road is slippery and its time to slip in to 4x4 and sounds like its slamin into 4x4 constantly

 

does anyone want to help me