I replaced the vacuum switch with a brand new one. Unless it was bad out of the box it should be working properly.

I'll do more troubleshooting later in the week and report back with my findings.

 

How did the lines look? Mine were pretty shot to the point where taking them off any connector would just break them. Is it possible you blew one of them apart when blowing out the ATF?

 

All the lines were in good condition. The PO replaced all the short pieces near the vacuum tank in the fender shortly before I bought it. I caught the vacuum fluid problem relatively early so there wasn't much in the lines. The only part that had a significant amount of fluid was the actuator and I replaced that with a new one. I also verified manifold vacuum (19") at various places around the system. I didn't check vacuum at the switch on the transfer case, however.

 

OK, it's been about two and a half months since last I did anything with this issue. I got busy with rebuilding the front suspension and I'm glad I did. With the front suspension much improved I can now return to the issue with the front axle not seeming to engage.

Today I put the Jimmy in 4HI, took the battery out, and pulled on the actuator cable manually. The cable pulled about a half inch. I locked it in place with a pair of locking pliers. I jacked up the right front wheel to test it. The wheel turned. I double-checked the front drive shaft and it did not turn. It seems to me that the front axle isn't locking in.

So what's the next thing to test?

 

look up "Bravada axle swap" and considering switching the whole set-up. I learned a lot about this issue on this site.

 

Time to take the shift cable housing off where it connects to the axle housing. Make sure the cable is connected inside the axle tube. If it is, you need to remove the right front axle tube and check the mechanism and teeth on the clutch shaft & axle shaft. Gotta remove the right front half shaft, which means the knuckle has to come off as well.... lotta messy work

 

Pay attention to Captain Hook, he knows his business. He helped me out a whole lot. Thanks again Captain.

 

Believe you me; I have a huge amount of respect for The Captain. He has given me a huge amount of help over the past couple years. I probably owe him a nice coffee cake by now.

Fortunately I have plenty of experience taking the steering knuckle off. I'm getting pretty good at it.

 

Thanks guys, have fun & work safely.

 

UPDATE: I was under the truck today reinstalling the remote oil filter block adapter because it was leaking from the previous installation. Apparently the o-ring didn't seat properly and it was leaking some oil. While I was waiting for it to leak after re-seating it I took the opportunity to remove the 4WD Actuator Cable housing and check out what was going on. Here's what I found:

The end of the cable was properly seated and clipped into the shaft that goes into the front differential. I pulled on the cable and housing as hard as I could and it semi-engaged the right axle shaft. It wouldn't engage enough to turn the right front wheel. When I rotated the front drive shaft with the cable pulled all the way out the cable and shaft would move in and out with the rotation of the driveshaft. I think that means something inside the differential is not fully engaging and the axle tube has to come off for further investigation.