Before you start read this: I've had loads of requests by people for the wiring diagram of this hybrid modification. I'm currently still working on it. I can give you the complete overview when my car is finished. This is what I've come to so far. If you have any information that might be of help for me (I'm missing a few signals still) please This e-mail address is being protected from spam bots, you need JavaScript enabled to view it .

Wiring up the 2JZ-GTE engine into the MA7 body

Yes, people, I've had loads and loads of emails of people how to wire up the engine into the MA7 body. I've answered most people personally, but the message was; wait and see. And here is the result.

What is the idea?

Mounting up the 2JZ engine into the MA7 body is not really difficult. But getting it wired up is very. The idea of wiring it up is quite straightforward though. 

First solution; Make your own wiring loom

Take the MA7 wiring loom. Imagine the 7M specific connectors to be gone. What is left? Well, on the 'passenger' side of the firewall we keep the connectors that mount the engine harness to the car, resulting in signals for the gauges, signals for the ECT (yes, the ECT computer is located in the car on an other location) and so on. In the engine bay we have two 'harness' connectors left, one for the theft deterrent buzzer and one for some power source (the EFI main relay etc.) Furthermore we would like to 'keep' a couple of connectors from the 7M harness, namely the temperature sender (for the combination meter), the VSV signal for the heater unit, the oil pressure sender for the combination meter and so on. Makes sense right?

Now take the 2JZ engine harness. Imagine cutting off everything that is not directly related to the 2JZ engine. What is left? We have the connectors for the ECU on one side and all the connectors for the engine on the other side of the fire wall. We agree that these signals are needed at the least for getting the engine running right? Now what is next. We need to find out how and where we can tap some signals that go into the car, for example information for the cruise control unit. On these signals we can solder the original connectors so that the new 'hybrid' engine harness fits without any soldering into the MA7 body. This will give us the cleanest result possible. What is left? A whole bunch of extra signals, available in the JZA8 body but not in the MA7 body. For example the shift lever indicator for the automatic transmission. What will we do with these signals? Well, we can always mount our own 'custom' additional connector to the wiring loom, for 'future' upgrades and custom wiring. Sounds neat?

Second solution; Make your own harness

The second solution I can come up with is only possible when you have the connectors that go into the engine harness of the 2JZ. If you have these, you can make some 'intermediate' harness between the connectors from the 2JZ engine loom and the connectors in the 7M. Again the approach will be quite the same, you first need to know every single wire in every connector! This solution is not possible if you want to extent the engine wiring harness (for example when you need to place the ECU at the right hand side, while it was originally at the left hand side). Currently this option is best for me, as I can use the clutch pedal hole in the firewall for getting the engine harness through. Then I can make a long wiring harness from the '2JZ body connectors' to the '7M body connectors'. Note this is long as the 2JZ body connectors are somewhere under the steering wheel, while the 7M connectors are behind the glove box! This all because I have the Japanese engine in my left hand drive vehicle.

How do we start?

Well, we need to know what signal goes where!!! We first make a list of all signals available at the connectors that go into the MA7 body. We do the same with all signals that are available at the JZA8 body. Lastly we make a list of all signals going into the 2JZ E.C.U. Signals will be classified in the following types:

Use: A signal to 'Use' is a signal coming out of the wiring loom / going into the wiring loom which we can use ourselves to make a new gauge or functionality. For example the transmission is in "N" signal. This is normally only used for a light in the dashboard. This is 'extra' functionality and not needed for normal operations.

Del: A signal to 'Del' is a signal we will delete from our hybrid. This signal will be left out from the car as the sensor or unit will not be used.

Hyb: A 'Hyb' signal comes from the MA7 and goes into the 2JZ or visa versa. A detailed description must be given where to find the signal. For example the RPM signal for the combination meter used to come from the 7M computer and now comes for the 2JZ computer. I expect most signals to be 'Hybrid'.

Add: A signal to 'Add' is a signal we need to create ourselves somehow from the MA7 body sensors to 'fake' into the 2JZ. This must be done with custom electronics. Currently I expect almost NO signal that needs to be 'added', but it might be possible we need a new 'speed' signal generated from one of the speed sensors (sensor 1 or sensor 2). We need some sort of A/D converter for the throttle percentage if you would like to keep the MA7 ECT computer or the TEMS.

MA7: A signal that is 'MA7' specific needs to be transplanted into the engine wiring from the car. This signal is 'body' specific, for example the progressive power steering solenoid or the temperature sender for the combination meter.

2JZ: A signal that is '2JZ' specific needs to be taken with us. All engine control signals are 2JZ signals, of course. Furthermore if we replace the cruise control ECU we have some specific 2JZ signals as well, which drive the cruise control actuator.

When we have compiled this complete listing, we must end up with a wiring harness with all 'Use' signals on one separate connector, to be used 'later'. The rest of the harness will feature the 2JZ ECU connectors first, then the MA7 body connectors (Hyb, Add and MA7 signals) and then we go into the engine room. Here we will find the 2JZ signals for the engine, some 'Hyb' signals and a couple of 'MA7' signals.  

If we are going with a connection harness between the original (unmodified) 2JZ harness and the 7M body, the idea is quite the same. On one hand we have the 2JZ connectors and on the other the 7M connectors. Somewhere in between possibly some floating connector with unused information. In this case we have to make some wires ourselves to temperature sensors for the combination meter etc.

So show me the signals!!!

Here we go. I've worked this approach;

1) Get all signals from / to the MA7 body
2) Get all signals from / to the JZA8 body
3) Verify how specific units will wire up, like the MA7 ECT computer (if needed) and the Combination meter
4)  Get all signals from / to the 2JZ ECU.

If everything is done, we can design and fabricate our own new wiring harness. Let's get it rolling people!

I'm referring to the page number of the electrical wiring manuals with a dash (#). The MA7 signals come from the 1991 model wiring diagram, the JZA8 signals come from the 1995 electrical wiring diagram. Note that some signals can be mentioned on various pages, this is especially true for +12V and mass signals.

MA7 body connection -> Engine wire harness
Taken from the Electrical Wiring Diagram 1991 model

When you leave out all sensors and the ECU from the engine wiring harness in the MA7 body (1991 model) you are left with the following connectors (names taken from the Electrical Wiring Diagram):

M1 - Located near the ECU behind the glove box. Handles most signals going to the combination meter
B1 - Located near the ECU behind the glove box. Handles mostly control signals
B2 - Located near the ECU behind the glove box. Handles mostly the ECT signals
B3 - Located near the ECU behind the glove box. Handles mostly the ABS signals
C1 - Located near the fuse box in the engine bay. Delivers the plus signals for the E.F.I. system
U1 - Located at the firewall. Just a connector for the theft deterrent horn, but it is called a connector joining wire harness, anyways.

Early model Supra < 88

Late model Supra 88+

Connector M1

Early model Supra < 88

Late model Supra >88

Early model Supra < 88

Late model Supra >88

In the pre 88 series the connector B3 is only seen in the NA models.

This 3 pin connector is only in the pre 88 Supra.

JZA8 body connection -> Engine wire harness
Taken from the Electrical Wiring Diagram 1995 model

When you leave out all sensors and the ECU from the engine wiring harness in the JZA8 body (1995 model) you are left with the following connectors (names taken from the Electrical Wiring Diagram):

II1 - Located near the ECU. 
IJ1 - Located near the ECU. 
IJ2 - Located near the ECU. 
EA1 - Located on the engine loom near the fuse box
EA2 - Located on the engine loom near the fuse box

The II1 connector is one big orange connector mainly used for getting all the engine and ECU signals to the combination meter and other dashboard components.

Delete units:

Vehicle speed sensor No. 1 for combination meter
Airbag units from 2JZ
Coolant temperature sender 2JZ
Fuel pump ECU

2JZ units:
ECU
Diode for Idle up -> Where is it? #76
Kick down switch!!!
Oxygen sensor!!
Manual shifting override switch
Optional Cruise Control Computer

MA7 units:

Progressive power steering ECU
A/C, blower, heater
Coolant temperature sender for combination meter
ABS computer
Oil pressure sender for combination meter
Cruise Control

So to get a long story short, let's see what we are going to use from the MA7 body and what we need from the 2JZ engine.

MA7:

Progressive power steering

Input is from the speed sensor in the combination meter (left in tact) and output to the solenoid. No further modifications needed

Cruise control

To make use of the cruise control unit from the MA7 body, we can leave most of the system intact. Here is an overview what needs to be connected to what pins:

Wow, that sounds simple! We can use the original computer as it is signaled with the original speed sensor from the dashboard. One problem we currently have, is how to mount the actuator in the engine bay so it can actually control the throttle valve. Well, that's not really difficult. If it doesn't fit in the 2JZ location, we just have to make the cable a little bit longer. I doubt we can use the 2JZ cruise control actuator with the MA7 computer, but we can always check that out later. Shall we check if we can use the 2JZ cruise control computer? Just to be complete.

And this sounds simple too! When we can convert the speed signal from the combination meter (no problem) to a signal for the cruise control ECU of the 2JZ, we can even keep the 2JZ cruise control actuator and use that cruise control computer as a bonus! Wow. Easy is that. Hope everything is as easy as this.

ECT

What about the ECT? The ECT in the JZA8 is controlled by the main computer as well. In case we want to keep the ECT computer so we can stay with the stock MA7 A340E, let's see what needs to be changed!

Again, it's just too plane easy. Two signals can be tapped straight from the 2JZ ECU and three signals need to be generated ourselves, just a simple A/D converter. That's it. If you want it, it is possible! Only side note I do have is that I don't know how the timing maps of the ECU are matched with the shifting points of the ECT. If anyone knows if the ECU does timing retarding or something when the ECT must shift, let me know. For what I can 'see' there is not a real relation between the two, otherwise there would have been a 'signal' between the computers. I don't know about the 2JZ engine,  but if you got the manual ECU there will be no timing maps what so ever.

ABS

For the ABS computer should really stay with the MA7 computer, IMHO. The 2JZ car came with four wheel speed sensors, while the MA7 has only one sensor for both the rear wheels. I can't see why using the ABS computer of the JZ car should be beneficial, if you really want to transplant everything of the JZ you can better just buy a mkIV car. Let's see how to wire up the MA7 ABS computer

Well, only two signals that need a hybrid connection, only if you go with the automatic transmission and shifter from the 2JZ. I won't even bother finding out what needs to be connected when we go to the 2JZ ABS unit.

TEMS

Some cars come equipped with the TEMS system. In order to keep this fully functional we need to feed the TEMS ECU the right input signals from the JZ ECU. Let's see what is needed when we swap the ECU.

As you can see another easy transplant. Only signals that needs to be made custom are the L1,L2 and L3 signals currently generated by the 7M ECU. Not much of a hassle I would say, we already needed to make those when we were going with the 7M ECT. Special design I would say. The rest is just plain easy!

Combination meter

The combination meter is one of the most important units to wire up. It is very nice to see what temperature the engine is running or at what RPM and speed. Let's see what is needed;

Not hard at all to wire it up. right?

The last unit to wire up now is the 2JZ engine ECU. Let's see what we need here

This connector is used for the Throttle Control computer only to be found in the Japanese specification Supra. I don't have much of the connection information yet, so if you know something This e-mail address is being protected from spam bots, you need JavaScript enabled to view it !