Hey guys, I have a v6 (3vze) 4x4 toyota 4runner (1992).
We are having an interesting problem. When driving, the trans won't shift by itself (It shifts fine when using the gear selector on the floor). As in, you start it, put it in drive, and try to go. It tries to drive in Drive gear. But if you select "L" it goes in 1st gear, but obviously wont up shift, so u bring it into 2nd manually (with the gear selector) and it shifts perfectly. So we know the solenoids are functioning. However, we have "fixed" it when we replaced the ECU with one from a junk yard, but then after a while it goes back into the same no shifting mode. So, we threw the old ECU back in and it started functioning properly (shifting automatically) again.

Anyone have an idea of what the problem is?!?

Sometimes it feels like you haven't shifted the lever far enough forward and adding to the issue is that it will often take several seconds for the 4WD light to go off.