I have a question about the auto-lock hubs on my 88 22R/MT 4Runner. I never had any issues beyond the HG on my '87 (it had manual hubs). Here is what happened yesterday:
I had finished reassembling the body after touching up some minor rust issues (tailgate) and installing the snow plow...I headed out to plow the lot at my shop and the 4WD wouldn't engage. I brought it in, raised all four wheels off the ground and diagnosed as follows:
The transfer case is engaging and the drive axle on the right front is turning but the hub will not stay engaged. I took the dust cover off and turned the axle nut and it locked in once and worked until I put it in reverse and it came unlocked. I tried the left front to no avail (I believe these run left rear and right front, correct?).
My questions are...is there something in particular that goes out on the auto-lock???
I've looked into a manual conversion and wonder if anyone has done that either??
Is there anything that I can do to make it work temporarily?

The auto hubs are known for wearing out, not sure exactly what wears out.

I did a manual hub conversion on mine for a few reasons: my auto hubs didn't work, I wanted to be able to shift in and out of 4WD on the fly, and I wanted 4WD in reverse.

The swap was very easy, it was as simple as removing the auto hubs, and installing the manual ones. There's a large nut (I think 54mm) that needs to come off, and you need a torq driver (T20 or T15, not sure) to remove all the parts from the auto hubs. The manual ones go on very easy with simple tools. I ordered new gaskets from the dealer, as well as new cone washers, and regreased and painted the manual hubs before installing.

It was a very easy install, and I'm no expert mechanic.

I had reverse in 4WD with the auto lock hubs. I pulled shrubs and bushes out at my house several months back. My understanding is that they are supposed to stay locked as long as there is power through the axles. Correct???
I just wanted to make sure that there is not anything else wrong and that the conversion to manual would take care of my issue.

Th most common problem with auto or manual hubs is lack of maintenance.

Try disassembling, cleaning, and greasing them amd see if they work.

If you do swap in manuals, make sure they're 86+.

Well, the maintenance issue makes sense. I've put only about 40 miles on the 'runner since I picked up my Supra in April so it has been basically sitting since (it was my dd before that).
This '88 was a replacement for my '87 (stolen 8/07) that I meticulously maintained. I've been finding out the longer I own it that it hasn't been maintained as well as was stated to me by the previous owner. This afternoon, I went to plow my lot in 2WD with some added weight in the back. I kept it in 4H the entire time even though I was only getting the right rear driving. I shut the truck off to move my Supra and when I got back in to pull it in the shop, the 4WD was working. So, for now, I'm going to leave it in 4WD since I'll need it for the snow storms coming this week. I'm still going to look at converting to manual hubs.