2002 trailblazer service 4w light on

i tried to use my autoxray scanner and also my autotap software to find out what the problem is with the 4wservice light. neither will show any trouble codes. is this a return tochevy to find out what the problem is or are their sources to find the problem. thanks tom

Are you having any problems with 4wd drive engaging?

I have a 2000 Blazer with Autotrac. The Service 4wd has lit up maybe 2 times in the 7 years I’ve owned it. Both times I disconnected the battery to reset the computer and the light never reappeared. I assumed if there was a real problem the light would reappear.

Last year I had to replace the vacuum switch that controls the front axle engagement, but the Service 4wd light did not appear.

i can not select any thing on 4 wheel drive options. it is lock in 2wheel