Service 4WD light comes on ..

I have a 1999 Chevrolet Blazer 4wd ZR2 Package (121,000 miles)

For the last few days the Service 4WD light comes on around 15 minutes into a drive. The light will go off on a restart and may or may not reappear for a day or so.


Any thoughts or suggestions? Any more info you need from me?

Thanks in advance for any help.

please use the search feature, this has been discussed many times.