lockup-mate®MX – The Isuzu D-MAX/MUX & BT50 Premium Torque Converter Lockup Kit

Installing an MM4X4 lockup kit can provide great benefits, which is why it’s a popular modification, especially for people who tow. Our kit can improve engine braking and driving responsiveness, reduce RPM flaring, reduce fuel consumption, and lower transmission temperatures.

We’ve had many, many enquiries over the last few years for an Isuzu lockup kit, so we’ve developed lockup-mate®MX for the Isuzu D-MAX, M-UX and Mazda BT-50. This blog discusses the unique aspects of the Isuzu 3.0L engine with the 6 speed transmission, and operation with our lockup kit. It is quite technical, so if you just want a general overview of the kit go to the website information page.

Intelligent Control

Our lockup kits are premium products because they are designed to properly and safely integrate with the vehicle using digital information from the ECUs via CANBus communications. They are not simplistic, manually operated or speed based on/off systems.

Our R&D program assesses each vehicle to determine when and how it will best benefit from an improved transmission lockup strategy. Every lockup kit we release is adapted specifically for that model for best performance, transmission protection, and drivability.

At the time of writing, our lockup kits have been adapted into 25 different vehicle variants across Toyota, Lexus, Mitsubishi and now Isuzu. This extensive knowledge has fed into the Isuzu kit’s development.

Each of these vehicle models/variants has a different transmission program which benefits from a tailored lockup strategy. And more importantly, this lockup strategy changes to ensure the transmission is safely controlled. This is why our lockup kits take time to develop and are adapted for every model we support.

The 6 Speed Isuzu - Similar But Different

Many manufacturers source their transmissions from AISIN in Japan. For example, the same 5 Speed and 6 Speed AISIN transmissions are used widely in Isuzu, Toyota, Mitsubishi, Lexus and more. The main differences between vehicles are the mechanical interfaces and the Transmission Control Units (TCU). So, you’ll find basically the same 6 Speed AISIN transmission will work very differently in a Hilux, Prado 150, 70 Series, Triton or Isuzu because the TCU is programmed to meet that individual manufacturer’s requirements and engine performance. This also extends to the manufacturer’s transmission control philosophy.

The Isuzu and Mitsubishi ‘MANUAL/SPORT’ mode works completely differently to a Toyota Prado, Hilux or Fortuner ‘SPORT’ mode – yet it is basically the same transmission.

Over time, although the transmission ‘box’ has become simpler, and they have moved the complexity into the software within the TCU controlling the valve body solenoids.

Same transmissions but very different software brains.

With Isuzu it’s no different. The lockup kit needs to understand and be adapted for the electronic brain of the transmission in this vehicle.

How is the Isuzu 6 Speed Transmission Different?

Every manufacturer decides to optimise their transmission program to suit that vehicle’s customer base. For example, a LandCruiser 200 Series and Prado are optimised for luxury smoothness and refinement whereas say, in the Mitsubishi Triton, the MANUAL/SPORT mode optimises for maximum lockup and faster, sharper gear changes that are not as smooth but yield a sportier feel and better towing performance.

What makes the Isuzu unique is they’ve optimized the transmission for fuel economy under light load.

Whilst this sounds great, it’s far from optimum for towing or for heavier vehicles (like with a canopy fitout). It changes up gears very early and has an high-reliance on the torque converter’s flex lockup mode. The Isuzu transmission computer is constantly making tweaks by deciding on which gear and which lockup mode to use (off, flex lockup or full lockup). As a result, it seems to be forever doing something which can feel frustrating to the driver.

(Flex lockup is like a partial lockup mode designed to limit slip and save fuel – if you monitor slip using your OBD2 Gauge you see about 50-80 RPM of slip in this mode.)

After driving this vehicle as part of a our R&D program, my assessment is “For goodness sake, just make a decision and stick with it!” I find the frequent and unncesssary changes to lockup and gear selection is frustrating, especially 6th gear.

Another observation is that the transmission oil runs a lot hotter than in other vehicles. This is primarily due to the lack of a dedicated front mounted transmission cooler and instead just a small engine coolant-based heat exchanger. Attention to regular servicing of the transmission is wise.

SafeLock® - Transmission Protection is our Priority

MM4X4 Lockup Kits include SafeLock® Protection, which are software features to protect the transmission from potential damage. Our kits will only lockup when it’s suitable and (most importantly) will unlock to avoid nasty effects such as shift shock, excessive clutch slip/wear, turbo surging or excessive load. They are designed so the driver can’t place the transmission at risk.

SafeLock® also includes the Emergency Brake Unlock feature that hands back control of the torque converter to the TCU to ensure there are no potential impacts to the tuned safety systems (eg, ABS, ATSC).

A simplistic speed ON/OFF based lockup kit strategy does not work for the Isuzu transmission. An advanced, digitally-controlled lockup strategy is essential.

The Isuzu is the first vehicle I’ve found which has operational regions where it will actually lose lockup under medium load and slip the torque converter clutch. Yes.. even-though the torque converter solenoid is applying full lockup pressure, the transmission slips and this risks wearing out the clutch prematurely.

This means there are specific circumstances where it is essential to unlock the torque converter (even at 80-90 KPH) and this is why a simplistic, speed-based lockup system may place a risk on the long term reliability of your transmission. After extensive R&D lockup-mate®MX avoids risking damage/excessive clutch wear in these regions and will automatically unlock. The kit is load sensitive, so don’t expect it to always stay locked under high load and low’ish RPM, as it needs to unlock to protect the transmission.

For this reason, we also do not provide a ‘manual lockup override’. Not only will this cause transmission error codes and very nasty clunks, but it is also not feasible for the normal driver to know how to detect and avoid clutch slip under full lockup. With transmission rebuilds in excess of $7000+, why risk it?

The Isuzu Gear Shift Strategy, and How to Get the Best from lockup-mate®MX

As mentioned above, the Isuzu optimises for fuel economy in DRIVE mode by up-shifting gears early, downshifting late, and it extensively uses the fuel saving flex lockup mode of the torque converter (more than any other vehicle I’ve seen!). Whilst good for fuel economy under light load, this strategy is not ideal when towing. When towing you want to stay higher in the RPM band and maximise full lockup. This is why some vehicles (like the new 70 Series 2.8L Auto) have a dedicated towing mode button for the transmission.

lockup-mate®MX will change the lockup strategy but cannot change the gear shift points, so the kit includes an LED positioned discretely on the A-Pillar to help the driver easily know when the transmission is in full lockup or not.

All the driver needs to do is keep the blue LED ON in the highest gear to achieve maximum benefits, and if it unlocks, downshift.

If the transmission is unlocked the LED goes OFF, and all you need to do is encourage the transmission to downshift a gear to put the transmission back where it is suitable for full lockup. This is done by either a momentary squeeze of the accelerator pedal (when in DRIVE) or manually downshifting using the shift lever +/- (in MANUAL mode).

When in MANUAL mode, we’ve also included a Slip Alert feature. After 5 seconds slipping under high load the LED will flash at you to remind you to downshift.

Use the blue LED is your towing guide and it will teach you how to best use the transmission gears. Some customers told me they used MANUAL mode but the transmission still got hot. This was because they were in the wrong gear. lockup-mate®MX will help teach you how to best drive in MANUAL.

The installation of the LED on the A-Pillar is optional, as we have also included the ability to display lockup status using your OBD2 Gauge (eg UltraGaugeMX, ScanGauge, CarScanner App etc). More on this OBD2 interface later.

Adjustable Load settings

When driving a vehicle which has a MANUAL gearbox the driver should avoid labouring the engine (ie avoid too much power at too low an RPM for the engine). We know that our lockup kits are installed into a wide range of vehicles which may have different engine power modification/increases or tyre sizes. This is why our kit is adjustable.

When driving the automatic transmission in MANUAL mode, the driver changes gears at the right times, just like with a MANUAL gearbox. However, when the automatic transmission is in DRIVE mode, the Transmission Computer (TCU) is in control of the gear changes. This mode has been programmed for the stock engine and tyres, not one with upgrades. Hence, depending on a particular vehicle’s actual power, there may be a possibility of the TCU labouring the engine, eg, holding onto 5th or 6th gear for way too long.

lockup-mate®MX provides the choice of three load settings (1 to 3) to cater for either different vehicle power setups, tyre sizes, or just the driver’s personal preference. Level 1 is the most conservative and Level 3 (the default) is Maximum. On Level 3 it will hold full lockup as much as possible to provide the best fuel savings and lowerst transmission temperatures. Then, the only reason it will unlock is if the speed/RPM is low or the SafeLock® feature needs to unlock to protect the transmission.

You can configure both DRIVE and MANUAL to use different settings. You can change from these default yourself using the kit’s Configuration Setting Mode.

PWM Control of the Lockup Solenoid is Essential

A fundamental element of a lockup kit is powering the electrical solenoid which controls the application of the torque converter clutch. This solenoid is a proportionally controlled valve that is adjusted by the characteristics of the Pulse Width Modulation (PWM) signal driving it.

A 0%, 25% or 50% PWM signal will change solenoid position and thus the pressure against the torque converter clutch plate. This is how the three torque converter modes [OFF, FLEX, FULL] are selected by the transmission computer.

lockup-mate®MX digitally controls the PWM signal in the exact same way as the factory ECU.

CAUTION: Be aware of other lockup kits which use a simple relay to switch 12V DC across the solenoid as in the 6 Speed AISIN transmissions this is known to burn out the solenoid after some time.

Again – transmission protection and performance is our priority, so we only use PWM electrical control which mimics the TCU signals.

No Engine Trouble Codes

The transmission ECU has advanced real-time diagnostics and is continually looking for anomalies. If a problem is detected it will generate a trouble code and go into a LIMP Mode. lockup-mate®MX works with the TCU to keep the transmission to avoid error codes. It even monitors the transmission temperature, and will not activate until it reaches the same temperature the TCU uses for lockup control. The kit will let the driver know by gently pulsing the LED during the warmup phase.

However, the kit does include a feature to reset the Check Engine Light (CEL) in case an error code is caused (for example) during installation by accidentally leaving a cable unplugged. This feature can also be used to reset any cause of a CEL. A simple double tap of the LED issues a reset command over the CANBus to the factory ECUs. Great if your car has a CEL issue and you just want to try resetting it.

NOTE: After a CEL reset, to fully and properly reset the computer from LIMP Mode you must turn the ignition off. In the Isuzu, even though the code is reset, the computers remain in LIMP Mode until it is power cycled.

lockup-mate®MX OBD2 Interface

A new feature in our kit is the inclusion of an OBD2 Gauge interface. We provide PIDs so the gauge (eg ScanGauge, UltraGaugeMX, CarScanner App) can be programmed to query information from the lockup kit computer. lockup-mate®MX is just like any other ECU communicating on the vehicle’s CANBus. We have also included a Vehicle Communication Interface (VCI) capability to convert information from other vehicle ECUs into a format the OBD2 Gauge can display, such as steering angle.

Currently supported parameters which can be queried from lockup-mate®MX are:

• Lockup Status – when in full lockup or not

• Pedal Position (%) – which also displays the equivalent % when using cruise control (cool!)

• Transmission Temperature (both Pan and Torque Converter sensors)

• Actual Gear (really useful when in DRIVE)

• Steering Wheel Angle – (3 choices, actual wheel angle, raw angle or simplified). Useful when reversing the van or sand driving (where are my wheels pointing?)

The VCI capability continues to operate even when the kit is turned off (using the LED/Switch). This ensures the useful information continue to be displayed on the OBD2 gauge.

Simple Plug’n’play Installation

lockup-mate®MX is simple to install and is fully plug’n’play. No wires to cut, or factory switches to be installed – not even a drill hole. It can be easily removed without any trace. Installation is easy and DIY.

1. Remove the glove box and a trim piece to access the transmission control unit (TCU) computer

2. Remove 1 x TCU connector and plug our harness connectors into it

3. Secure the load resistor/heatsink and control unit with cable ties

4. Clip the LED/Switch onto the A-pillar trim

5. Plug in the OBD2 cable into the vehicle (an OBD2 Y-splitter is included so you can also connect an OBD2 gauge)

6. Run the self-diagnostics and then road test to confirm operation. DONE.

Summary of the Key features of lockup-mate®MX

• Fully Plug’n’Play Installation – simple DIY installation and is easily removed without a trace

• Advanced Digital Control - for fully automatic lockup control

• CANBus Interface to ECUs – to determine key data like speed, gear, load, 4L etc.

• Separate Lockup Strategies for DRIVE and MANUAL

• Lockup in High Range, 3rd – 6th gears. No manual lockup, nor in 2nd and 4L to avoid transmission error codes and nasty clunks.

• Lockup when coasting – for maximum engine braking

• Load Sensitive – for transmission protection and drivability

• SafeLock® - for driveline and clutch protection

• PWM Solenoid Control – for maximum performance and to avoid a burnt out solenoid

• Lockup Status LED – easily visible to assist the driver to maximise benefits

• LED/Switch – LED is also a momentary switch to toggle the kit on and off

• LED Slip Alert – in M, flashes LED to advise the driver when to downshift to regain full lockup

• LED Auto-Dim - linked to the headlight being ON, with manual override for daytime headlight use.

• LED Warmup Pulsing – kit automatically deactivates while waiting for the transmission to warmup.

• Self-Test Diagnostics Mode - to confirm operation after installation

• CEL (MIL) Reset – to self-recover from an installation related error code

• OBD2 Interface - to allow extra vehicle parameters to be displayed on your OBD2 gauge

Conclusion

Every one of our kits is unique to the vehicle supported, and the adaptation of lockup-mate®MX for the Isuzu uncovered some surprises and challenges. As you’ve read, behind a seemingly simple blue LED is very complex control logic to ensure you obtain the best possible performance without compromising transmission reliability and safety.

The blue LED is located discretely on the A-pillar and in the driver’s peripheral vision to provide clear lockup status and helps achieve the best performance benefits. No factory switch slot is required.

An OBD2 Gauge interface has been provided to allow key vehicle parameters to be monitored when towing or driving.

Like all our kits, the design is carefully considered and includes features that specifically enhance towing and provide improved drivability in your Isuzu or BT-50.

Happy travels!

Cheers,

Marshall