Shift at Will - Automatic Transmission

on Wednesday 14 November 2007
in A-Z Index - Everthing is listed in here > Transmission

When to do it

Anytime as the job is inside.

Installation Time: About 4 – 6 hours as I was extra careful and double checked each move against the manual.

Prior to purchase

Contact Maciej at Ess-racing via his email (link on the site) and confirm that your Automatic Transmission Control Unit (ACTU) is compatible with the SAW. As I had an Australian spec car mine initially was not compatible, however after many email exchanges and some mods to the SAW the system is even better than before and I think now fully compatible with all spec Zeds.

Tools you will need


Probably the most important aspect of this job is to ensure that you have prepared yourself correctly. Download the installation (and the user) manual from the Ess-Racing web site at . Print the installation manual in colour if you possibly can as this will make the job a little easier. The installation manual is really quite good and this Tech article is really only supplements the manual.

Next read the installation manual until you fully understand what is to be done. I read the manual at least three times or more from the time I ordered the SAW until it arrived. I found that by the time I received the SAW I had a full grip on what was required to be done. One thing though – you can’t just pick up the manual and start installing. You have to understand what is being done and why. Careful attention to the correct placement of the wires is essential.

This is what you get for your money


  • Power module (lives between the ACTU and the wiring loom to the transmission
  • Control Unit. (lives where the OEM clock currently resides)
  • Gear Display unit {optional}. (Can live anywhere you want to put it). I consider this display an essential extra
  • The gear change switches. I recommend the flush mounted stick on type with the optional raised rubber centre

Next I recommend you sit down with the manual identify each of the wires from the control unit that are not part of the plug. From the picture below you can see that I have marked each wire with a piece of tape identifying which wire goes where.

When it came time to installing the control unit I found that the Australian Spec car also had the ACTU mounted in a slightly different location (a few cm further away) and I had to peal back the outer plastic cover of the wire loom to split loom into two separate ones.

As I was not planning to fit a Fuel Pressure sensor I identified those wires used for this task and taped them back against the main loom. Recommend you determine if you need to split the loom first as I had to do this exercise again later.

Installation Step 1

Mounting the Control Unit.

The first step is to disconnect the battery as the AT control unit has power into and out of it even when the ignition is off. Next mount the control unit where the OEM clock is located. To do this remove the centre panel as shown. Note the location of the screws (1 to 4) and the two clips (5 shown the other in same location other side) that hold the panel in place. Screws 1 and 2 are located behind a couple of small clips that need to be gently eased out. The two clips (number 5 thick line) need some effort to pull out. I used a thin screwdriver to ease them out, but a confident person can just take hold either side in the location 5 shown and give it a rather heavy pull and it will pop out. There is a separate Tech article on this site if you need additional help on how to remove this. I apologise for out of focus picture (shaky hands). Follow the instruction manual procedures.

Once you have the centre panel out you need to fit the control unit to where the OEM clock is. Feed the wiring loom through an appropriate place so that it feeds to the passenger side. The Control Unit is best left dangling until all other connections are made as it fits to the centre panel and is quite awkward to fit as the wiring loom is just long enough to make the distance. Don’t forget to take off the protective cover on the face of the control unit before fitting the control unit to the centre panel.

Installation Step 2.

Tapping into the computer (ECU).

Again the instruction manual is quite detailed in this area, however one thing that is not made clear is that when tapping into the ECU loom it is essential that you don’t cut any wires all the way through as apparently this can upset the wire resistance and cause inaccurate readings to be transmitted, especially the transmission oil temperature line.

Remove the carpet and the 4 x 10mm bolts from the wooden cover exposing the ECU and ACTU. Number 1 is the ECU and number 2 is the ACTU. ECU and ACTU are both held in by 10 mm bolts. I recommend a ¼ inch ratchet socket drive with a 3 inch extension for ease of removal.

I found here that there was not enough wiring loom to reach my Aust Spec ACTU and the terminals of the computer so I split the loom as shown. Number 1 are the wire to the ACTU and number 2 are the wires that need to be tapped into the ECU. I understand the Jap spec car has the ECU plug closer to the ACTU so the SAW wiring loom is probably long enough for a Jap spec car.

If you have to split the loom do so carefully so as not to cut any wires. I recommend you use a Stanley knife and make a small cut in the outside cover of the loom and then pull the plastic cover back over itself using the Stanley knife to help with the stripping as shown

The picture above shows the loom after being split. This exposes an extra wire which are not used as shown by the screwdriver. Rather than cut it off I folded and taped it out of the way just in case I needed it later.

Now comes the bit that requires some degree of finesse. Tap into the ECU lines as per the instruction manual taking care to double check that the wire colours match that of the manual and that you can positively identify the pin number as per the diagram in the manual as a double check. You will need to undo the ECU loom as shown above. Take your time and be sure to get the correct wire. Tapping into the ECU is not as difficult as it might seem. Just ensure you have the correct wire and then using the Stanley knife held across the wire scrape away until the bare wire is exposed (do not saw as you might cut the wire). Clear away the insulation and solder in the appropriate SAW wire. Cover with insulation tape. This is quite a fiddly job as you have your head buried deep into the passenger side foot well and you really need three hands. I had anticipated this problem and had purchased a set of “helping hands” from Dick Smith Electronics for around $12.00. These have two adjustable clamps which can be positioned to hold the wires firmly while you solder them. A good solder joint is essential for correct operation. The picture below shows the Over Drive connection being made.

Once you have the SAW wires soldered to the ECU wires repack and retape the ECU loom as shown.

Installation Step 3.

Installing the Power Module to the ACTU

This next step is probably the most difficult, although by now you should be confident at what you are doing and will be moving along at a reasonable pace. Six wires from the ACTU need to be cut and a couple need to be SAW wires need to be tapped into the ACTU loom. I strongly recommend that you carefully identify each wire that needs to be cut using the procedure described in the ECU section before cutting a wire. Start with the two 12 Volt wires as they are easy to identify and it doesn’t matter if they happen to get mixed up (these are the only ones you can mix up and get away with it!). See picture below.

Next insert each wire as shown noting the “mirror” image layout. Cut one wire and install. Cut the next wire and install. Do not cut all at once as the potential for confusion will be high. Follow the instructions in the manual carefully. This is where is pays to have read the manual more than once. When you have installed the power module this is what it looks like. Note the mirror image of the connections.

Tap in the remaining wire to the ACTU and tape up the loom again. It is quite a squeeze and if I had to do it again I would have cut the ACTU wires further away from the ACTU plug to give me more room to work. DO NOT FORGET TO BOLT DOWN THE EARTH LEAD.

Note: The Australian Spec car proved to have a compatibility problem and required the installation of 150 Ohm resistors tapped into each of the lines leading from the ACTU to the power module with the resistors going to earth. This is not shown, but I believe will be incorporated in all future units sold as they provide the ability to shift between Auto and Manual mode without stopping. A big improvement.

Installation Step 4.

Tapping into the Cruise Control Circuit

The final bit of work that has to be done in the foot well is the connection of the shift control lines into the cruise control wiring loom. In the Aust Spec car the cruise control unit is mounted under the ACTU. After the previous step this is a breeze. Follow the instructions and tap into (do not cut through) the appropriate cruise control wires as shown below.

After this step double check everything is in place and connected then refit the ACTU and ECU onto the forward bulkhead. Do not insert the wooden cover until after the test drive (in case of problems).

Installation Step 5.

Installing the Optional Gear Display

This display is offered as an option, however I consider it an essential requirement for efficient control. The display is designed to fit in front of the clear plastic cover between the speedo and tacho. I wanted to fit it behind the clear plastic, however when I finally got to this area I found it was not suitable and opted for the default location. Removing the speedo is in itself a separate Tech article and can be found elsewhere on this site, however the only noteworthy point is that I needed to file a half round section from the dash panel where the display sat so the wire could be routed behind the panel. Here is a picture to give you an idea of what is required. Note the arrow showing the half round section.

Installation Step 6.

Installing the Gear Shift Buttons

On the home stretch now. Deciding where to put the shift buttons was in fact quite hard. Prior to installation I decided to pretend that I was shifting manually and tried various simulated positions for the buttons. As I drive with a quarter past nine style grip I decided in the end to place the buttons on the back of the steering wheel in a position such that my two little fingers and ring fingers could reach the buttons. This has proven to be very effective and I am quite happy with the choice of location. Personally I would stay away from drilling holes in the steering wheel cover as the SAW could be removed quite easily prior to selling the vehicle and I wouldn’t want to try and sell the car with a couple of holes in the cover of the wheel.

Remove the steering wheel pad as described in the manual. Tap into the cruise control circuits as described in the manual and then replace the steering wheel cover. After refitting position the buttons where you want them to go, mark the position then use a strong solvent cleaner to remove any grease or oils and then stick the buttons on the wheel. I recommend using the raised rubber extension pieces as they make location of the buttons by feel easy.

Note the raised section of the buttons. And the finished product. Buttons are behind the steering wheel T section on the leather, not plastic insert of the rear of the steering wheel.

Installation Step 7.

Vacuum clean the foot well area to remove any loose wire bits and solder etc. Reconnect the battery and then the fun bit starts. Take the car for a test drive. One thing that is not said in the manual is that the first time you turn on the ignition you may see the AT check light give an error indication. Just recycle the ignition once to clear the error signal. That should solve the problem. Also note that until the AT is placed into lock up mode the OD light remains on even though the OD button has to be left in the ON (depressed) position. Follow the instruction manual and make sure that the full auto function works properly before switching to manual mode. The manual mode will lock the car into the specified gear and will not allow a shift down or up unless you command it. In effect you also gain another gear as the lock up function can be treated as a gear. You now have control over all 5 “gears” not just 4 as in the normal AT. I often use 4th gear around town now as I stop AT lock up from occurring. Caution don’t put the AT into lock up below 60 kph or oil temp of around 55 C. In other words drive the car for about 4 km before putting it into lock up and you will not have a problem. The AT will go into lock up below 55 C in manual mode but the auto function will not let that happen in order to prevent unnecessary loads on the gear box. So when in manual mode treat it the same.

If all goes well return to the garage and replace the wooden cover and carpet on the passenger side foot well.

Got problems

If you have problems then it is back to the drawing board. Check all connections are made and ensure that the mirror image connections of the power module are correct. If all else fails contact Maciej via the email link on his web site.

ossible Bugs

The SAW has many extras functions and I have tested many of them. One known bug which requires a Control Unit software fix is in the Accel function. The Accel function permits the driver to record and store his 0 – 100 kph time to 1/10th of a second. Unfortunately following the run the lock up function of the AT plays up and you need to stop and turn off the ignition for a few seconds then turn it back on. That solves the problem. (Minor inconvenience). I presume Maciej will address that problem and future units should be bug free.

Possible Needed Extras

Having never had a readout of the transmission oil temperature I found that this function was a useful setting to be displayed during normal driving. Unfortunately the readings gave me cause for concern as they were in the low to mid 90 degree range and the book says 50 – 80 degrees C is normal. I may be having high readings because I run Redline Racing AT oil (at $106 + per 3 litres) and that gives a stickier oil than normal and hence is likely to run hotter. Just the same Ess-Racing recommend the fitting of an additional oil heat exchanger which I have done (around $150) and the car now runs 10 degrees cooler.

I recommend you run you car in normal full auto and monitor the oil tem reading to see what was normal. Then run it in manual mode and note the difference. If I drive normally in manual mode the temps seem about 5 degrees hotter. If I give the car a bit of stick then it runs about 7 – 8 degrees hotter.


Wriiten By: John Dolby (dolbs) Ph: 0417 486 616