torque convertor lock up

As Brian said, transmission spucialist. How long since the tranny oil has been changed?

Cheers
Pop

Yep, the truck is what 16 years old and only done 82,000 k's. Sounds like either your odometer is a bit sus or it has done a lot of sitting around and maybe moisture in the transmission fluid has gummed up something. Try changing the oil and have a good look at the suction screen. That maybe all it needs. If that doesn't do any good take it to a transmission mob.

Cheers
Pop

The only thing that holds a torque converter clutch ON is hydraulic pressure.
The fluid may be the wrong fluid or the valving is sludgy or sticking and although the solenoid releases the pressure actuating the spool valve to turn it on is sticking.
IMHO very unlikely to be the actual clutch itself and very likely to be fluid quality, viscosity when cold, or some gumming of the controlling spool valve.

Until you get up to a reasonable speed the clutch should never be actuated and especially just after starting and reversing etc.

Not sure about Toyotas but all the other autos I have driven do not lock the converter in the lower gears. They also do not lock the converters in the higher gears until the fluid warms up.

If the converter is locking it sounds like there is a mechanical problem in it somewhere.

Kiwi Ray
Before it gets a fluid replacement. Take it for a run where the fluid WILL get hot and WILL lockup and unlock the clutch as many times as you can. That should begin to shift deposits and any sludging.

That is so the fluid flushes repeatedly through the troubled area with some frequency and likely to move something.

Any person draining a transmission and and not also dropping a hose off and allowing the usual torque conv. return flow to be dumped and therefore POSITIVELY changing the dirty fluid in the converter is not really doing the full flushout.

The torque converter contains, as much as or more than, the transmission itself, so when the trans is refilled the hose should still be off and engine run until it bubbles and then refilled again and run until it bubbles OR the fluid runs clean and new.
This HAS to be done repeatedly until it is clean. Then the hose put on and the proper fill then done and checked.

Nearly ALL service places DO NOT fully flush a transmission.
Expect it to use at least 15 litre for the flush if done properly. If it doesn't it hasn't really achieved anything.

Cheers
Ross M