Torque Converter Lock-up?

[Diverse4runner]

93 4runner 3.0 194k miles

For about two weeks my transmission would pop in and out of TC lock-up. It would get up to temp drive it for 20 min and it would pop out.

Now it wont engage at all. All gears are fine 1st through OD shift fine no hesitation no slippage nothing.

1. Does anyone have any ideas
2. Is there any write up on how to test a lock-up solenoid. (I was reading that the tranny will not throw a code for the lock-up solenoid only 1 and 2 solenoid)
3. Could it be the TC? there is no shuddering and slippage from it.

Ive price some rebuilds in the area all are around 1,700 but I dont have that much cash to throw at it.

Please Help Guys

 

[ToyoTech]

i had a similar situation. it wouldnt go into lock up unless i drove for a really long time or when hot out. mine ended up being a stuck open t stat. the lock up works only when the engine is within operation temp. even tho my temp gauge was looked normal. it was just a hair low that you really couldnt tell and caused the lock up not to engage.

 

[Diverse4runner]

Its not a temp problem I have had that happen though. Vehicle gets up to temp fine because it still will go into OD just wont lock-up.