1999 Chevy S10 Blazer Pushbutton 4X4 switches do not light up and 4X4 does not engage Help?
Your 4x4 fuse probably blew out.
The 4wd in the 1999 Chevy blazer is electronic, you just have to push the button. If you have pushed the button and it doesn't engage, it might be a vacuum line. The lines are made of rubber and over time they melt. It costs about $25 for a new metal line. Also, the 4wd is under the battery. If you take the battery out, you might notice that a line got disconnected accidentally.