(Auto) Manual Lock-Up TC Kit For Prado

[sunny120 Junior Member Find all posts View Profile Close sunny120]

From memory I think I paid around the $450 mark for the Wholesale lock up kit, definitely makes a difference on freeway towing and in low range going down hills. Transmission still changes gears both ways with it on. It will only stall the car if you have the optional valve body upgrade (about $2k from memory). Not hard to fit, just got to make sure you cut the right colored wires from the TCU.

[Mozz Member Find all posts View Profile Close Mozz]

I've not read this but are you saying you have built a full plug and play version with automatic deactivation when slowing down to a stop.

[Dabeanian Member Find all posts View Profile Close Dabeanian]

The Prado 5 speed auto will absolutley unlock the torque convert in 4th and 5th gears geratating a lot of heat.
When locked up the auto trans fliud will be below 50 degrees. If towing at highway speeds it is quite common to have a load that will cause the torque converter to unlock and slip without down shifting, allowing the engine to produce more torque to satisfy the load. In this situtation the trans fluid temp can head north of 100 degrees within a couple of minutes.
A perfect example of this is the over temp issues with the 150 auto trans. It is the same transmission as the 120, it has just been reporgrammed to hang onto taller gears longer in an attept to improve fuel ecomony. This causes the torque converter to slip for longer before down shifting, hence the over heating.
I have an auto trans fluid temp gauge fitted a can clearly watch what this happening when towing. If my trans is slipping in 5th and the temperature is getting too high, I simply manually pull the transmission back to 4th which increases the rpm causing the torque converter into hyraulic lock up and reducing the fuild temp.

This manual lock simple allows you to over ride the torque converter electronic lock/unlock and stopping the transmission from slipping when below hydrauilc lockup rpm.

As for whether a heavy duty valve body is needed in a Prado for first gear lock up, I have had a couple of conversations with wholesale automatics and they indicated that it "probably" wouldn't be needed in a Prado. But I need to speak with them some more and get a definative answer.
Leachy

Thanks for the write up Leachy , answered a lot of my questions that I did assume ,
Away in Darwin from Perth at the moment towing the caravan loaded at about 2.3 ish , noticed if towing in D , ( 120 kd , 09 )
Which isn't that often , at about 90 and 1700 rpm on a slight decline wind assist situation it was fine. Then I would notice the revs would go up ( going up a slight hill ) to about 2100 / 2200 ish but didn't drop to 4 , if I manually dropped to 4 the revs would go to about 2400 at 90 ks ,( locked I assume ) so I assumed I was getting slip in D , haven't got a gauge for auto but did fit a cooler so don't expect temps to go up to high,
Will ask more questions when we get back about the prows and cons about a lock up kit for D , but still think it might be overloading the gearbox, but really can't get it in my head just yet.
Cheers Alan,