I have a 1998 chevy s10 and it keeps going into four wheel drive on it's own. Just started having this problem. I'll be driving down the road and all of a sudden it switches from two wheel drive to 4hi. There seems to be no rhyme or reason; it does it at slow and high speeds.

Anyone have any ideas?

 

perhaps a faulty switch? (I assume the 98 has the dash push button?) my 99 did, but my 95 was on the floor. Does the light just switch or can you feel the front axle engage? If it is engaging that cant be to good, I'd definetly take it in and have it checked.

 

Have you noted any service lights on the instrument panel?

Do the 4X4 panel lights sequence normally when key is turned on?

If it was a chafing wire - you could have one person under truck listening for transfer case buzz while another moved wire harnesses ... with key ON of course.

 

Front differental control module?