Hi and Thanks...I have the old style 2002 blazer and the 4 wheel drive switch was stolen from the dash. Harness cut and switch removed..so I got new harness and switch just put in and there are lights coming on in background but no lights on the 4 buttons 4hi-4lo-2wd-auto4wd- and the 4wd does not work.Service 4wd light is on also.Everything worked perfect before switch was cut and removed. I have called around to chevy dealers and can not get answer if the 4wd has to be reprogrammed? Any help appreciated.