There have been many variations of implementing this system.

The system I have built is based on the work of many others on here

http://www.patrol4x4.com/forum/nissan-patrol-gu-gr-10/patrol-auto-converter-lock-up-11914/

I have just finished putting it all together after procrastinating for months, since electronics is not my strong point. But it was successful, and I'm happy with the result.

I made a version that takes a feed from the Vehicle Speed Sensor so that the system stays in factory mode until the speed is over 60kph, when it is possible to switch the override on and lock the converter. When speed drops below 55kph, the system disarms, so you can't leave it locked when it shouldn't be.

Here's the circuit I used, you can find all the part numbers on the other thread and then you can see whose work I have based it on.

I have also done this mod and its pretty handy at times. thought id add some pics of my install.

Mounting the relays near the ECU

Making up earth straps for the relays

Arm switch off and on

Torque converter Engaged LED

Other relays under the dash

Foot activation switch

Part number for footswitch (Jaycar)

Part number for LED light.

I installed a switch as well, but find it a mixed blessing, so simplified the entire circuit so that it only operates off a foot switch like in your photo and an override switch that arms/disarms the circuit (partly hidden under the console). This is the circuit that I used:

I find the lockup useful when going up hills (towing or not towing) and I know that the engine has the power to hold the extra gear. It's also useful for acceleration, going from 2nd to 3rd and OD.

Cheers

Ray

I use it all the time. Find it great. car uses abit less fuel prob 0.5L per 100. Around town if traffic light enough so im not turning it off and on costantly ill turbo OD off lock the TC and cruise in 2nd and 3rd gear. When you put your foot down car pulls like a train with it locked.