My 1998 z71 locked itself in 4wd hi when i crossed the railroad tracks by my house and my front end locked up I let it set for 10 mins and it was fine wondering what could cause it and why its not lifted it has 33in tires on the back 31in tires on the front with 16x12 american racing wheels

 

Is your transfer case push button or manual shift? The range fork in the np241's (manual) can wear and cause it to pop out of 4hi. Never heard of one going into 4hi though.