I'm not sure what's goin on. I just bought this 97 Blazer LS 4x4 for $800. figured I got a good deal.

When I press the 4Lo button... the button flash for a second, then shifts into 4 wheel drive. However both 4Lo AND 4Hi lights are on. I know it's in 4 wheel drive because I can definitely feel a driving difference from 2 wheel.

When I press 4Hi, it does the same thing, flashes, shifts into 4x4, but both 4Lo and 4Hi lights are on.

When I press 2Hi, both lights flash, then it shifts back into regular 2wd...

Which 4x4 mode is it actually shifting into?

 

Don't panic, person that sold it to you probably did because of that! This should be an easy fix for you. I'm assuming that the 97 4x4 control unit is in same location as a 98!!
Carefully and slowly with a couple of flat screwdrivers or just your hands depending on condition of the clips!
Pull your passenger side plastic off the floor that you step on getting in the truck. Now after that's up the plastic panel to the right of the passengers right foot . Carefully remove that, you'll see a little ecu that's the 4x4 computer. Remove ground wires, (clean) unbolt computer, disconnect wiring harness . Now comes the important part , to buy a set of torch tip cleaning instruments and use the correct size to clean the wiring harnes, after that take a small 1/8" standard screwdrive and clean any pins sticking out of the computer that are green! They bend very easy so you can just barely touch them ! Break them off and it's over with!
Now reassemble the kick panel is a little touchy going back on sometimes the plastic doesn't get into the clips right!
Good luck if that don't solve it most likely you'll start getting a very soft grinding from front axle eventually! That's a small gear gone bad in front axle! Also very easy fix!
I'd google 4x4 fix for blazer switch and you'll probably get a video showing you what I just told you!