Torque Converter

Lockup Kit

LandCruiser 200

Install and road test

If you've watched my initial review of the 200, you'll know that I've always been less than impressed with the behaviour of the automatic transmission.

This article and video will cover a major improvement to its operation, thanks to a system to adjust the operation of the torque converter lockup function.

The problems with the 200's Aisin transmission

Compared to almost every other modern automatic transmission, the 200's Aisin AB60F transmission behaves very poorly in a number of areas.

With the torque converter unlocked, change points -except for the change to 5th gear- are generally too high in the rev range to take advantage of the twin-turbo diesel engine's flat torque curve. This means the engine revs far higher than it needs to, generating additional wear and consuming more fuel than required.

The 'sports shift' system doesn't work like any other light vehicle I have ever driven, only allowing you to restrict changes into taller gears rather than actually holding the gear selected. For example, if you select S5 then all it does is restrict the gearbox from changing into 6th. It does not hold 5th gear preventing a downchange to 4th. Again, this means you cannot even manually take advantage of the low-down torque of the engine.

But by far the most annoying 'feature' of the transmission is the operation of the torque converter (TC) lockup. The TC lockup function fully locks the engine to the gearbox, improving fuel economy and preventing heat buildup in the transmission fluid. The 'Cruiser's TC essentially only locks in 5th and 6th gears, at high speeds and under light throttle. By contrast, most modern automatics are programmed to engage the TC lockup as soon as possible and in as many gears as possible, particularly when operating in 'sports shift' mode. This is probably best illustrated by a table comparing the operation of the 'Cruiser's lockup with that of the ZF 6-speed transmission in my GT:




Landcruiser 200 (Aisin AB60F) torque converter operation

Falcon GT (ZF 6HP26) torque converter operation

* In practise, the 'Cruiser rarely locks in 5th gear while under acceleration. It tends to remain unlocked until cruising speed is reached, eventually locking in 6th. Then, under load it unlocks and changes back to 5th, then re-locks in 5th after a few seconds.

Coming up with a solution

The best way to fix the programming of the transmission would be to modify or replace the computer which controls the gearbox. This option is available for many transmissions around the World, but in the case of the 200 it's exceedingly difficult. While most vehicles have a dedicated Transmission Control Module (TCM), the 200's transmission is controlled directly by a combined engine/transmission ECU, and (at the time of writing) nobody has managed to successfully 'uncouple' the transmission control from the ECU. This means that it's currently impossible to customise the behaviour of the transmission, so you're pretty much stuck with the existing shift points and sports-mode operation.

What can be changed is the operation of the torque converter lockup, by overriding signals to the unit and sending phantom signals back to the ECU to prevent a check-engine warning. At the time of writing, there are three different companies manufacturing torque converter lockup systems for the 200:

One option is the European-made ECON*lock. Still the most automated option available, it's also the most expensive at about €1390 (A$2000). The manufacturer also claims it's the safest option, because it generates a pulse to operate the lockup valves, similar to the factory system.

Next up is the Wholesale Automatics manually-operated lockup switch. At a cost of about $520, it performs a lockup of the torque converter through manual operation of a dash switch, at any speed and in any gear between 2nd and 6th. Like the ECONlock, it uses a pulse to activate the lockup valves.

Then there's the system I've chosen, produced by Stefan at Richards Auto Electrical in South Australia. It's a speed-sensitive automated version, with the driver able to preset the speeds at which the TC will lock and unlock. The kit costs about $700. They also produce a manual system similar to Wholesale's switch, for around $300). Rather than the solid-state pulse used by the ECONlock and Wholesale systems, the Richards system uses a series of Bosch relays and a resistor to activate the lockup valves.

In my opinion, having the system automated to lock at a preset speed is by far the best option for a device like this. Its operation requires no input from the driver, so there's no need to constantly think about locking and unlocking it as you drive at different speeds. You maximise the fuel economy benefits of the system. I've also added a 3-way (on-off-auto) override switch, which allows me to revert to factory operation and also force lockup at lower speeds than I've preset, should the conditions require it.

Update June 2016: Several companies are now offering remaps or reprograms of the transmission control functions of the ECU. I have made several enquiries in an attempt to get full details of what parameters can be changed, and to what degree. However little information has been forthcoming. I will continue to investigate this option.

IMPORTANT

The "Installation" section should not be taken as instructions. It is simply a documenting of the procedure I followed for my own installation. No warranty is provided as to the accuracy of the information, and/or whether it applies in your situation or to your vehicle. If you're not qualified and/or don't have the correct equipment, get the lockup kit fitted professionally.

  • There are potentially lethal dangers resulting from the use of power tools.
  • There is the potential for expensive vehicle damage from improper installation.

If you undertake your own kit installation, you do so entirely at your own risk.

Equipment required 

  • Assorted spanners and sockets
  • A drill/cordless drill
  • Thread locking fluid (eg Loctite 243 or 263)
  • Pliars
  • Flat and phillips screwdrivers

ebay-unit-1024X160

Installation Tips

Richards supply comprehensive installation instructions with the kit. I followed these instructions in the video above and found them to be accurate, so I'll only add a few tips below and also document the wiring of the ON-OFF-ON switch, which allows me to choose between On, Off or speed-sensitive automatic operation of the lockup.
Step numbers correspond to the supplied instruction steps.

Step 1:

  • Tape the kit wires to a piece of rigid wire, then pass it through one of the two nipples in the Toyota grommet, after cutting the end of it off. I already had some wires in these nipples from previous installations, but they still passed through reasonably easily.
  • It's not mentioned in the supplied instructions, but I advise connecting the orange battery wire via a fuse for additional safety. I just connected mine to one of the spare terminals on my accessory fusebox.

Step 5 and 7:

I have covered the dash pull-apart previously if you would like any tips.




Step 6:

See below for the changes required to enable On/Off/Auto operation. Note that this change is not required for current kits, as they now include the 3-way switching.




Adding a switch to enable ON / OFF / AUTO operation

While I generally wanted set-and-forget speed sensitive operation of the lockup kit, there are times when it would be handy to override the speed setting and lock the TC manually, such as long downhill runs for engine braking, or long low speed climbs to keep the ATF temperature under control. This can be achieved by installing an ON-OFF-ON switch, where one of the ON positions gives automatic control and the other gives manual override.

There are plenty of such switches available, typically with I O II markings, but I wanted an illuminated switch design that was neat and clearly showed which mode was active. I thought I'd found the perfect one, being a Cole Hersee 58312-AG, available on special order through Repco and Bursons for about $20 plus any order fee. Unfortunately, after testing it I discovered that the illumination is wired ridiculously, so that the opposite light illuminates from the depressed side of the switch. For example, if the green side is down, then the amber light is on. But because I hadn't found any suitable alternatives, I persisted with the switch, disassembling it and rewiring the lighting so that it operates logically. I then printed some labels to apply to the switch, giving the result you can see in the photo.

Note that I removed the "Idle Up" switch to install the lockup switch. It serves little purpose in a warm country like Australia.

Installing the switch into the lockup kit circuit:

  • Instead of connecting the green kit wire direct to the back of the dash power outlet (Step 6), run a new wire from the power outlet up to the POWER IN terminal of your switch.
  • Run the green kit wire to one of the POWER OUT terminals of the switch. This gives automatic operation.
  • Run another wire from the switch's 2nd POWER OUT terminal back to the lockup kit. Then splice it into the green wire that runs between the relay block and the control box of the kit. This connection overrides the speed controller, giving you manual operation.

You now have three modes:

  • ON - This will lock the TC at any speed in any gear except 1st and reverse. You'll find that the vehicle will seem a little rough and jerky at low speeds, and it will lug at low revs when you're under about 60km/h. It can be very useful for engine braking or low speed hillclimbs, but is best used in combination with S mode on the gearbox so you can select a suitable gear.
  • OFF- In the centre position, the transmission reverts to factory operation. Handy when you take it to Toyota for a service.
  • AUTO - The torque converter will lock and unlock automatically at the pre-selected speeds.



Adjusting the lock and unlock speeds

The lockup kit comes preset to lock at 78-80km/h and unlock at 74-75km/h, assuming you have standard tyres (larger tyres will affect the settings).

As I have larger tyres and I also wanted to reduce the lock speed slightly, I had to change the preset values in the controller. It's a reasonably simple process:

  • After completing the installation, remove the 4 screws retaining the top of the controller box, and slide out the controller. You'll see a display plus a series of 4 black buttons below the display (labelled U, D, S, R) and dip switches above the display. Be careful not to damage the electronics via a static discharge.
  • To find the setting you want, you need to drive at the speed you want, then push the 'R' (read) button at the bottom right of the display. The display will show a number, which you need to take note of. For safety, have an assistant push the button, instead of trying to do it while you're driving.
  • To change the LOCK speed, push up the 1st DIP switch in the bank of 8, then push the 'U' (up) or 'D' (down) buttons to change the value, followed by the 'S' (set) button.
  • To change the UNLOCK speed, push up the 1st and 3rd DIP switches in the bank of 8, then push the 'U' (up) or 'D' (down) buttons to change the value, followed by the 'S' (set) button.
  • Return the DIP switches to the down positions. Never change the position of the DIP switches in the bank of 3.
  • There must be a minimum difference of 5% between the LOCK and UNLOCK values. In my case, I chose LOCK at 49 (~77km/h) and UNLOCK at 44 (~69km/h).

It's up to you which speed to set the lock/unlock at. I initially wanted a lower speed, but found that the vehicle lugs in Drive when below about 65km/h with the lockup engaged. You can overcome this by selecting a lower gear (eg S3, S4), but that would almost defeat the purpose of automating the system, and I think the fuel economy benefits would be negligible. Note that according to Richards, if you want to set an automated speed below 35km/h, you need a different controller box.

Update for Unichip installation:

Although I have neither experienced nor heard of any failures in the lockup clutch following the installation of a lockup kit, I decided to err on the side of caution after the installation of a Unichip and exhaust delivered a 50% power and torque increase. I have now disabled the TC lockup when at high throttle positions. This was accomplished by having the Unichip installer program an earth output wire from the Unichip, which switches off at above 50% throttle. I then used this output to switch the TC lockup kit on and off via a standard relay.



Testing and results

Following installation I drove a test loop, once with the lockup engaged and then again with it disengaged (ie: standard factory operation).

The loop was 75km in length, and consisted of around 25km of undulating 80km/h rural roads, 20km of hilly 80km/h highway, 20km of 60-70km/h suburban roads and 10km of flat 90-110km/h freeway. Even though the TC lockup was only applicable for around 3/4 of the loop, it resulted in an overall 9% fuel economy improvement from 12.8l/100km in standard form, down to 11.9l/100km with the TC lock engaged. The largest difference occurred under heavy throttle at 90km/h, where the ultragauge reported almost 50% lower consumption thanks to the TC being locked. I expect that when towing my camper-trailer at highway speeds, fuel consumption will be improved by 20-30% on average.

The fuel economy improvement only tells part of the story though. The other part is drivability, and the difference is remarkable. Once the TC locks, the vehicle feels far more responsive. You can feel the torque of the big V8 powering you forward, instead of watching the tacho (and fuel consumption) leap with little acceleration to show for it.

This one modification has totally transformed the highway performance and economy of the 200. This is the way Toyota should have programmed their gearbox to operate.

Update 17/10/14 - Check engine light

Since fitting the kit several months (and about 10,000km) ago, I've twice experienced a "check engine" warning related to the TC lockup. The exact combination of warning lights displayed are: Check engine, 4-Lo (flashing) and Traction Control.

The code given by the computer is P2757, which indicates that the computer sees that the TC is locked, but thinks it shouldn't be (or visa-versa). After speaking to Stefan, it seems this is an occasional side-effect of the lockup kits where they can't fool the ECU fast enough, causing the warning under certain circumstances when the TC locks or unlocks.

There's no side effect of the warning (limp mode etc), and there's no damage being done. The only issue is the lights on the dash. If you have an Ultragauge or Scangauge II (or similar), you can reset the warning immediately. If not, switching off the vehicle for a couple of minutes usually resets the warning (although it is stored in the ECU). Otherwise, you can disconnect the batteries for about 30 seconds.

It seems to be a rare occurrance and I'm not concerned about it, but it's worth noting that this can occur for reference.




Comments / Q&A