Need written info on 91 4WD problems

I got a 91 4Runner 4WD with Auto Trans. Problem: 4WD will not engage. I read other posts and answers, stuff about an actuator, ADD?, (other TLA's too), vacume hoses, grounding switch, changing front diff. fluid, etc. I'll look into this but does someone have some definitive information on the web or books specifically on this 2nd generation 4Runner's 4WD mechanical stuff? I need to read, not go on info that will send me chasing my tail. All I have now is the Haynes Repair Manual, nothing about 4WD really.

Dave

http://personal.utulsa.edu/~nathan-buchanan/93fsm/

it should show the front diff. or the transfer case.

When you engage the 4wd does the light on the dash come on?? If so it's the add probably. If the light doesn't come on there is two wires coming out of the transfer case that realy the transfer case is in 4wd therefore engaging the ADD system. Hope that helps. I had the problem of the light not coming on and the two wires were disconnected when I changed my clutch. Over looked them and pulled the tranny separating the two wires.

I found the problem, it was the vacuum hose that goes down to the front diff. It was cut. Fixed it for free and off I went in 4WD. No problems till 4 hours later when I found out my tranny is shot.... Bummer.

Thats CHITTY man!! sorry to here that!