Ive noticed my 4wd humming while im driving, so i tried troubleshooting my 4wd and after I had raised the truck ive come to a conclusion.

The truck will go into 4hi/lo fine. But it wont go back into 2hi from 4hi unless i push the button a few times and put it in neutral, or it will come back into 2hi if i go from 4lo to 2hi.

I also notuced that i do not have a vac switch on the case. So i believe it is an nv236, however i have a 3 button switch in my dash


So my question is would a 3 button switch in place of a 4 button cause this problem?

Ill be acquiring a 4 button switch later today to try, and ill update.


Thanks for the help!

 

Buddy with the 4 button switch is being difficult. So im still waiting to receive it.
While i wait to acquire it can someone chime in on this, i think the proper switch should lrobably fix my problem..?

 

https://blazerforum.com/forum/tech-articles-diy-29/4wd-front-axle-clicking-when-2hi-goes-away-when-4hi-4lo-41226/
The link explains how to diagnose the front axle issues you are having. Look at your rpo code in the glove box. IIRC, NP1 is the 3 button switch and NP8 is the 4 buttn switch, with auto 4x4.