I have a 2007 4Runner Sport with 85,000 miles on it. I purchased it in 2011 with 45,000 miles from a dealer. I immediately had it inspected and pronounced "in good shape" by another Toyota dealer, and for the first few years god good use from it.
About a year ago it began to refuse to engage 4WD. I took it to a mechanic who replaced the actuator and pronounced the problem solved. Because I was unhappy with some of the other work this person did I took the 4R to a Toyota Dealer and paid them to inspect his work. They told me the transfer case need to be replaced and that the center diff was "locked". The estimated cost was more than $4000 as I recall.
I did not proceed with their recommended repair but instead took the vehicle to another local mechanic - who has also done work for me and who is supposedly a transmission specialist - and had him diagnose the problem. He reported that they could get the 4R into 4WD, but only on the lift, not on the ground.
After recovering the truck once more I tried putting it into 4WD myself. It seemed to me that it would do so, but that the center diff was locked whether I engaged it or not.
I found another transmission shop who said he personally has owned 6 Toyota 4WD and could diagnose the problem. Two weeks and $120 later he returned the 4R, un-repaired. When I asked him if I could continue to drive the vehicle in 2HI, he recommended that I sell the vehicle instead. He said "Your Toyota is very confused. It is going in and out of 4WD all on its own. Spend the money and trade it in on a new one."
I really don't want to sell it: Apart from the cost of acquisition and repairs, I like the body style and I think that for the cost of a 2016 I could replace the entire drive train on this one.
I am beginning to suspect an electrical problem may be part of this, but I have read here that there are vacuum line leaks that may be responsible as well. So what does the forum membership have to say? Dump the truck or keep trying to solve the problem?
Thanks for your replies.