Torque Converter Lockup-- What Speeds

[watsea Member Find all posts View Profile Close watsea]

I did a search but nothing popped out for me.

For a 2019 Prado with auto transmission, does anyone know at what speeds are required for the torque converter to lockup for 5th and 6th gears?

[GeeWhizz Senior Member Find all posts View Profile Close GeeWhizz]

I think it's a bit more complicated than just speed. Load and throttle position play a big part of the equation too.

Just looking at some of my logged data show 4th gear lockup at 48, 51, 54, 55, 57, 58, 59 km/h but also unlocked at 56, 57, 59.

I haven't got any recordings from when I've been on the open road. I checked for 5th and 6th gear TC lockups in the metro area, including freeways but, despite engaging 5th and 6th for shortish periods, the TC has not locked.

[watsea Member Find all posts View Profile Close watsea]

Thanks for your reply GeeWhizz.
I have wanting to do some towing of my van and was hoping that there might be a speed on flat road where I could get some ATC lockup in 5th, while towing in S mode. You're correct, playing with speed and the gears, it is very hard to get much chance of real lockup while in 5th or 6th gear.
Though while towing my van, I have found that when using S4 mode (as recommended), ATC lockup in 4th gear seems to hold longer if the Cruise Control is activated. Exhaust Gas Temperature does increase more during any increase in engine load while holding 4th longer.
My real aim is try to get better fuel economy. I'm reasonably happy with the engine power. Any hints are welcome.

[gwaite001 Junior Member Find all posts View Profile Close gwaite001]

Hi. As GeeWhizz notes, the TC is complicated and based on speed, load, throttle, cruise control, and whatever else the computer is programmed with. The best way to manage is a Stocklock; it's quite difficult to manage manually. With the Stocklock on once over 82kph the TC is off and the Prado will cruise & overtake much better by simply using the gears. Also gives a cooler TC oil temp!