First a personal note:
1. My grandfather, father, and myself call Chevy's "Shove it or Leave It". Yep, like my brothers '63 Nova. Who press fits oil pickup tubes?! Not AMC!
2. I also swore I would not buy a SUV.
3. I am a convert to my 1991 Chevy S-10 4WD and am restoring the old bat.
4. It has 343K miles!!! How is that possible for a '91?!

The 4WD auto locking hubs are a bit of a mystery including the mysterious module with one wire coming out of it (detached) under the battery. The diaphragm I know, but is that module related somehow?

As a former mechanic (Dad and I specialized in AMCs), I'm not very familiar with 4WD beyond the obvious components: transfer case, control console (mine works!), and some other drivetrain components. Never worked on the hubs, though.

Does anyone have a diagram for the 4WD system including vacuum and electrical components?

Stupid thing has me stumped and someday I'll try, again, to work on the manual hub control cable. There is one installed but NOT working or hooked up. Not sure if it's even the right one!

Any questions?
(I'm also not sure about using the old OBDM1 codes system, need to research that)

The mystery module!

Yea, needs paint job and has WRONG grill! I need those!

 

Welcome!

Perhaps someone will be able to post some pages out of a service manual for you.

I had a 92 2-door for a while. I needed a 4-door so I got rid of it. I did like the 92's short wheel base though.

By chance, years after I sold it, I found myself parking opposite my old 92 Blazer!