4x4 engage problem, slip light and brake light on

so, I have had a bit of warranty work done on my rig....... now, the slip light will stay on for long periods of time as well as the brake light. I just had a new driveshaft deal done( funky u-joint or something ) and now the 4x4 high does not want to work properly. controls say it is engaged but the front does not work like it used to. What would cause the slip light and brake light to stay on for long periods of time and the 4x4 to not work properly. The rear end has been replaced as well.

I looked through some posts but couldn't find anything that went along the same lines as my problem. If I missed one I am sorry. Don't know what the flame factor is like on this site....

slip and brake light stay on in 2wd as well.