Toyota A340E Control

Toyota A340E Control

There are a few different version of the Toyota A340E transmission, but this break down will cover the most common 2JZ-GTE version found in the USDM MK4 Supra. Even then, there are still a few version of the USDM MK4 Supra A340. If you have farther questions regarding a specific A340, please submit a support ticket

                                                                                                                                     Transmission Wiring 

These transmission have 4 plugs, 3 on the drivers side, and 1 on the passenger. (referencing LHD cars)
1 - Direct clutch input speed
2 - Main valve body plug
3 - Output shaft speed
4 - Transmission PRNDL switch 

These transmission do not have a line pressure sensor, but it is recommended to add a aftermarket one when trying to control with a standalone ECU. We offer a 250psi pressure sensor that will work well here.

Speed sensors 
The speed sensors are 2 wire VR style sensors, these both can be used if you have the open IO, but just the rear speed sensor is needed for vehicle speed. 
The front direct clutch input is listed as NCO by Toyota, the rear speed sensor is listed as SP2. These will both use SPI inputs to the Haltech. 

There are some models that have a 3rd speed sensor that is located on the right rear of the transmission, I will attach a image below.
It is a hall effect sensor and is used to drive the OEM cluster. You do not need this when wiring the A340 to the Haltech.

Valve Body 
The main valve body plug can be a 8 pin or a 10 pin depending on the year. I will go over both here.

These all have special terminology from Toyota to describe the individual pins and their functions. Both connectors have all the same pins and functions minus the 8 pin connector missing the transmission temp signal. This can be a separate connector on some.  

SLU : Torque Convertor Lockup

SLN : Accumulator Pressure Solenoid

SLT : Line Pressure Solenoid

S1 : Solenoid 1

S2 : Solenoid 2

For the wiring to the Haltech, it is pretty straight forward.
You will need 2 high side outputs for the S1 an S2 shift solenoids. These pull 1 to 1.5 amps, so if you have a Elite 1500 or 2500 you can use the DBW outputs to drive these solenoids directly. If you do not have those outputs available you will need to use low side DPO's to trigger relays to power those shift solenoids.

The torque convertor lock up solenoid, line pressure solenoid, and accumulator solenoid are all ground side switched, so any open DPO, or unused injection output will work fine here.

If your transmission has the internal oil temp sensor in the valve body, you will use any open AVI and a pull up resistor in the software to read the internal transmission temp. There are some A340's that have the temp sensor external with its own 2 wire connector. You can wire that one the same way if you want.
You can also add a aftermarket temp sensor to the transmission pan if you want as well.

PRNDL Switch 

This is responsible for telling the ECU which gear you have selected on the shifter so it knows what gear to command the transmission to be in.

These wires are all 12v switched and can be wired to any open input on the Haltech, but this takes up 6 inputs and is often not ideal.  There are companies that offer a PRNDL switch that converts all 6 signal wires into one signal so you can save inputs though.  Next Level Motorsports offers a A340 gear position convertor for this.
HT-038010 - PRNDL Signal Convertor 

                 Transmission Tuning and ECU Setup 

Selector Position 

Now that you have the wiring done for the transmission, it is time to open up the Haltech NSP software and get the tuning side complete. Start selecting the "Transmission" node in the ECU navigation tree on the far left side of the tuning software. You will want to select the following settings:

If you are using direct inputs from the PRNDL switch, instead of a signal convertor, you will want to change the selector position type from "Voltage Input" to "One per position"
Like so:

Once you have selected your selector position type, you can go to the wiring tab and assign the wires you used, again the signal convertor uses one input and without that you will need to use 6.
If you are using a signal convertor, you will follow the next step to get your ECU reading your shifter position.

Now select the "Selector Position" tab in the ECU navigation tree. If you are using a signal convertor you will have a voltage and tolerance per position. Turn on all the position you are using, in the A340E there is park, reverse, neutral, drive, 2, and low (or 1). Once all these are turned on you can go through all the position on the shifter and calibrate the voltage reading per position. It will look like this, note your voltages will be specific to your signal convertor.

This should take care of the PRNDL switch set up to the Haltech ECU. To test you can open a number display in the NSP software and select "Gear Selector Position" and this should read what gear you select on the shifter itself.

Transmission Control

I will go over the basics to get a A340E up and running, but there are TONS of other features you can add to your control strategy if you want.
Start with your "Transmission Control" node and select the following options. This will cover the basics on how you want to control the auto shift tables. 

Next go down all the sub nodes under "Transmission Control" and use the following information:

Auto Mode Shift points  - This is the table the tells the transmission when to shift. This table is based on engine demand and gear, the table value is MPH. This can be changed if you want, but this is the easiest way to tune in my opinion. The Y axis is the gear change, so 1->2 would be the 1st to 2nd up shift, and 2->1 would be the 2nd to 1st down shift.

When you are tuning the shift points for 2 and the low (1) setting, you will just stop the ECU from shifting to those gears using the 4D tuning axis on this table. 
This is done by selecting the cells for the upshift you are trying to prevent and maxing them out. The ECU can still make the shift if you reach the RPM shift point setting detailed below, but this would only happen if you hit the limiter set below.

If you are using a manual mode with paddle shifter, or a sport mode where you have more aggressive shifting strategy's, you would add both those options to the 4D on the auto shift point table and tune them according. Not all add this on the A340's, but if you are interested email in to and we can help!  

RPM Shift Point - This is a fail safe so you do not over-rev the car if your auto shift point table is set up incorrectly. This can also be used as a WOT shift table.

Shift Inhibit - This will stop a shift from happening. Most commonly it is used if you are using manual mode with some paddle shifters and you want to prevent the transmission from down shifting if the RPM's are too high in the gear you are in. This information is figured out per car since different ratios can change the allowable down shift RPM. When in doubt, set it low and work your way up. 

Shift Duration - This is how long the transmission takes to shift from gear to gear. The ECU uses this information to help with line pressure control during a shift. The rule of thumb is start with larger numbers if you are unsure how your transmission shifts.  You can log transmission control shift progress to see when the shift is started and then look at RPM to see when it drops and settles into the next gear to figure out the time it takes to complete the shift if you are wanting to figure out the exact data needed for this table. 

Output for Gear - This is not used when you select a specific transmission in the main transmission setup page. 
Wiring - This is where you assign the outputs you used to control the 2 shift solenoids in the A340E. They are high side, so make sure the output you used is set to high side and able to supply 1.5 amps. 

Line Pressure Control

This function is used to control the line pressure of the transmission while in gear and during the shift. This will aid in keeping your A340E alive with added horse power from your engine. 
You do need to be careful though since too much line pressure will make the shifts harsh when you are just cruising around and not enough line pressure can make the transmission slip.
There are 3 types of control in the Haltech for line pressure, I will go over the most basic, open loop.
If you are wanting more information on the other tuning methods, please refer to this link -

For open loop you are just setting the duty cycle you want to pulse the solenoid at, and nothing more. This is the most basic, but it is effective. 
The A340E frequency is 300hz and it is a bleed style solenoid, so 100% DC would bleed off as much line pressure as possible and 0% will bleed off no line pressure. 
There are tables for in gear, shifting and a correction table for fluid temp. Rule of thumb is for higher horsepower, you will want more line pressure.
Here is a basic table to give you a idea on it can be set up.

Accumulator Back Pressure Control

This is something I have not seen a huge benefit in using with the A340E transmission. The accumulators job is to help soften the shift when going from gear to gear, but with the line pressure shifting table, it is a little redundant. I will still provide a example table so you can see how it should be set up. The solenoid use a 300hz frequency and it operates in the same fashion as the line pressure solenoid with 100% being the most amount bled off, and 0% being no line pressure bled off.

Torque Convertor Lock

This is going to be used when you are in 4th gear and cruising. You DO NOT want to lock the convertor when you are under a heavy load and making a lot of power. 
Here are basic setting to start with for the A340E

The lock point is the MPH you will lock the convertor at once you have met all the other conditions. It will be determined by what MPH you are typically cruising at in 4th gear. 45 MPH is a safe place to start, but can be adjusted depending on your gearing and tire size. 
The unlock point is the MPH you unlock the convertor at if you are still meeting all the conditions, but slowing down. This is usually set 5-10 MPH lower than the lock point setting.

The lock duty cycle is PWM output to the solenoid to keep the convertor locked and not slipping. Here is a good place to start.

                                                                  Flat Shift 

You will not use flat shift active time since you are a auto and the flat shift function will be triggered from the auto transmission control function already. 
Here is the run down on how it is linked and works.

First we have the flat shift link option, this tell the ECU you want to use flat shift with your auto transmission control, and if you want it to start the cut before or after the shift has start and if you want to use throttle blip. 
Start the cut after the shift has started for a A340E.

Next we have the flat shift link delay. This is the time it takes from when the shift is commanded, until the shift is actually completed. This is set by logging the shift request and then watching for when the RPM drops into the next gear. Here is some reading for this -
This is a table for a A340E with a shift kit, these number will be larger with the stock valve body.

Next you are going to the flat shift settings. You will need to pick the flat shift mode, either timed or while active.
Timed give you a table to tune that lets you set the amount of time you want based on whatever axis you want, RPM and TPS are common here. 

While active follows the transmission control flat link delay table and uses the values you set there to determine how long to keep flat shift active. You will need to make sure that your trigger option is set to "triggered by transmission control function" for this to work properly.

For the torque reduction settings, you can pick what kind of cut you want, the recovery method, shift direction, and some conditions for when it is allowed to work.
I recommend and ignition cut and retard and ramping them together once the cut is over. This is the smoothest option I fell.

Lastly we have cut percentage, ignition retard and recovery time tables. 
The cut percentage is going to be the amount of cylinders you want to cut for the time requested from the flat shift link delay, or the flat shift torque reduction time, depending on your settings. 
These tables can be mapped over RPM and TPS, Engine demand, flat shift active time, etc. 
The ignition retard is the same concept as the cut, but it is just removing timing instead of removing the ignition event all together.

The recovery time is how long the ECU takes to ramp the cut and retard back to the normal commanded ignition timing. If you remove the cut and adding the timing back instantly, you will get a harsh shift and can damage the transmission over time. Typically at WOT you will feed the cut and retard back instantly, but for cruising it is done over time.

That is a general overview of the A340E transmission and some base setting to get you up and driving before you get to dialing in the transmission control. If you want to read more about the Haltech transmission control function and setting, please have a look at our Haltech Knowledge Base. There are tons of articles and explanations going over all the transmission control functions.
I will like the Knowledge base below.

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