For me,
The loud clicking developed in the Passenger Front Wheel Hub.

This was after 1 of 2 events:
* Changing between 4wd/2wd while at freeway speed
* Changing from 4wd to 2wd while backing up a 2,000lb trailer, up hill, with the wheel cranked over to the stop (aka Bound Up) in Compound Low

... I had a Ripped Passenger CV Axle boot so I swapped the Passenger Front and inspected the hub. When it all went back together the clicking was not gone. I inspected the Driver Front and found the Automatic Locker Hub clutch had spat out of its resting location
* Ring was cracked
* Spring was loose

The actual mechanism appears the same Left/Right. On passenger side the clutch remained in the hub (secured by a large diameter ring) while I pulled away the spring loaded locker. On the driver side the Clutch Spring, Ring, and retaining ring were a mess. The clutch ring and spring came out with the locking assembly, with only a retaining ring left behind (may be using the incorrect names, only skimmed the 1,460 page manual).

Proof of Repair Thread
* 110 Videos in a Youtube Playlist (L O L) depicting the entire adventure
* ​​​​​​​

All I did was remove the hub clutch ring, re-pack the clutch ring, thread in the spring clutch, goober it with Marine Grease and ... 42 miles later, the 2WD / 4WD selector works as well as it ever has on this 200,000+ mile vehicle.


Here is what the assembly looks like on the bench (64th video)

Anyhow - I am not "Off Roading", just trying to use the truck to trailer loads to dirt roads. I will let you know if/when it fails. So far I have 42 miles on the "repair" including backing a trailer up hill in reverse on dirt.

-methods

P.S. That is NOT a "How To" video sequence. That is just a log of how I worked thru the problem to a solution I am (so far...) satisfied with.
P.S.S. Yes I know they need "special grease" and that 99,999 other people already switched to Manual Lockers. This is a thread for those who wish to understand and restore the original functionality.

 

My name is "methods" from Endless-Sphere. I am not here to trick you, sell you anything, or provide Technical Advice. I just turn on the camera while I am trying to solve problems and post a thread when I have it working.

You will find a bit of a Vacuum around the SR5 4Runner as everyone has replaced with Manual Lockers. Those links above depict a different adventure that may or may not pan out long term.

* the 1988 manual is posted on my website in PDF, non-OCR
* the WayBack machine has links to other manuals
* this forum is the best resource for 4Runner solves
* Wikipedia explains some keystones around vehicles that have the hated automatic lockers

I only found 2 other videos while searching.... look for things like
* Changing out the Axle
* Changing out the Rotor

Along the way they have to remove the Automatic Locker. It comes right out (AFTER) you re-thread the 6 retaining alans that are always stripped. The taper bushings pop right out if you hammer them.

This is not Professional Advice
If you work on your Toyota, please only operate it OFF ROAD ... lol

-methods

 

The automatic hub isn’t hard to do, with the FSM. Without the FSM it wouldn’t be hard to get things slightly out of alignment, and then would break easily as things are tightened down. Especially that coiled spring with the big tabs. The diagrams in the FSM are key to making sense of the written instructions.
Yep smacking the bolts with a hammer does loosen the conical washers/spacers, but use a brass drift. Even better, put a nut on the end of the bolt first.