'96 Sierra 4x4 problems

I have a issue with my 4 wheel drive. I had an issue where I wasn't getting any response to my actuator when I would change from 2hi to 4hi or 4lo. I got on here and got some answers...went back and traced the wiring to the switch and found out that one of the wiring had come loose, I hooked it back in and crimped it on for a tight fit. - Now when I put the truck into 4hi, the actuator responds! which is good, but that bad news is, when I put the truck in 2wheel it stays in 4hi and won't go back into 2 or even 4lo.

What might be the problem?

There is a switch on top of the transfer case that sends power to the actuator. It is located where the 4 wheel drive shift lever goes into the transfer case. I replaced the switch, (a $35.00 dealer only item) and now mine works great. Only took about 15 minutes to replace.