2001 Jimmy 4x4 problems

I just bought this jimmy The 4x4 did not work at first found a vac line unhooked at the acutator hooked it up and now it seems to go into four wheel drive the lights switch on dash you can hear the electric motor under the vehicle but when you switch to 2wd the lights say it is in 2wd but when you back out of a parking spot you feel a drag or a wheel hop as you back up and turn out of a parking spot or turn sharp in a parking lot. Could that cable be dry and not allowing the front end to disengage ?

Does all 4W lights come on for a bulb check key on?
Will it shift to 4W low and back to 4WH>
Any check engine or check transmission/transfer case lights or ABS brake lights on?
The front axel can be checked by jacking up front end and see if it is locking out and in.
MT