Offroad-Express

Hey all, recently my torque converter has stopped locking up above 85k, at first it started doing it every now an then, but now it doesnt lock at all, even when out of O/D.
Fluid level is good, stall tests were ok, im out of ideas and my workshop manual doesnt seem to have anything in it about the lock up side of things

The converter lockup is controlled by the ECU....
So may have issues there..
Also it has some criteria for the ecu to let it lock...
Like engine / water temp.
Also brake pedal not depressed etc etc...

And the last thing is the solenoid in the box could be faulty..

Go and read this site..http://www.autoshop101.com/
Particularly the technical articles.
In there you will find toyota's basic operation of their systems including the automatic transmission.
Then you can pick off each bit that allows the lockup to work.