97 Jimmy 4x4 problem sle

I have a 97 Jimmy sle with a 4wheel drive issue took it to my mechanic and this is what is going on when he put it on the lift the 4 wheel drive work fine but when it's on the ground it disengages any idea what could be causing this. It is electronic not manual. :uhoh:

I have a 97 Jimmy sle with a 4wheel drive issue took it to my mechanic and this is what is going on when he put it on the lift the 4 wheel drive work fine but when it's on the ground it disengages any idea what could be causing this. It is electronic not manual. :uhoh:

Off hand could be short or bad ground or lose plugin.
But first get it on a 4W drive capable scanner and check for codes and problems.
Post back any codes.