Been trying to figure out why the 4wd isn't engaging on my 91 4runner. Long story short, I applied vacuum to passenger side port of the actuator and 4wd still wouldn't engage. Removed actuator and discovered that the sleeve that locks the axel doesn't want to move far enough toward the differential to lock the axel. I'm referencing the "Defeating the ADD system" article for the proper position of the sleeve. Does this mean I need to dig into my differential to figure out what's wrong or am I missing something? Thanks

 

Pictures are worth A million words .

Has the 4x4 in this vehicle ever worked??

With out pictures it is hard to tell if parts are missing and being a Toyota could very well be the case.

Is the sleeve traveling the full range of motion or is something causing it to hang up??

That is what you need to figure out

 

I dont know if its ever worked, new vehicle to me. The sleeve has a range of motion of only about a half inch.
As far as it goes to the drivers side.
As far as it goes to the passenger side.