I just purchased a 1999 silverado 2500 knowing the 4x4 has issues. The lights on the dash panel switches are intermittent and the switch does not seem to function. The panel says to service 4WD.

What are the common issues with the 99 4x4?
Where can I get a replacement dash switch?
Is there a way to pull the codes without having a machine or take it to a shop?

Aside from not going into 4wd everything seems to be fine.