I have a 2001 Chevy Blazer LT and am having issues with the 4x4. My car starts in 2hi and I can switch it to auto 4wd, but not back to 2hi. And no matter what my 4hi and 4lo don't work, they won't even blink. I have replaced my entire vacuum system and buttons. Please help!

 

What noises do you have coming from the transfer case control module (TCCM)? The TCCM lives behind the passenger side kick panel.

When they go bad you will hear the relays clicking several times. I had to replace mine many years ago.

Some have reported that the electrical connector for the TCCM can become corroded and cause problems.

I don't know if there are codes to read but perhaps someone else knows and perhaps has some other ideas to suggest.