Toyota Supra NA-TT Conversion – Wiring – Part 3

Summary                                          Part 1
Removal of stock parts           Part 2
Wiring                                                Part 3   – You are here
Aristo engine differences      Part 4 
Installation                                     Part 5
Final thoughts                              Part 6

Wiring is probably the most daunting and cumbersome for most completing this conversion. If you do not know much about wiring or aren’t confident reading wiring diagrams then please have an auto electrician or workshop do the work for you.

At the time I spent a while reading the diagrams, looking at the differences and it probably took me a few weeks of studying and identifying what I needed to do, there could be small differences between year models and SZ/SZR so the information below is all on my experiences.

I’m going to give you the best advice here – Track down the end state engine loom and stock ECU, and this will save you countless hours of troubleshooting and won’t require too much custom wiring. If you track down a front body loom for the fuse box area then it should be all plug and play. There are so many variables to this step and this is the process I followed which worked for me, I was lucky enough to find a VVTi engine loom and ECU out of a supra.

The last step in all of the stock removal should have the engine loom out of the way and all of the connectors unplugged, ensure the GE engine is out and that the GTE is ready to have the loom installed (If required).

Also last thing – Please check the first page of this guide for links to all the wiring manuals, pinouts and parts required.

Below is a general guide to the custom wiring you will need to do

  • Fuse box EFI1 / EFI2 wiring
  • Fuse box ECTS-i wiring
  • Potentially o2 sensor and water temp sender on engine wiring loom (On aristo engines)
  • If you want the electric fan for the A/C you will need a 30amp FAN fuse with a relay/wiring – I decided against this
  • If you want advanced ABS and traction control buttons you will need that wiring and ECU – I also decided against this

The GE and GTE share the same fuel pump ECU and fuel pump, the only difference is that the GE only has 1 EFI relay and the GTE has 2 EFI relays.EFI2pic

EFI1 relay and fusing –

EFI relay 1 is already setup on 2JZGE but the fuel pump ECU uses 12v from the EFI1 relay the 2JZGTE uses the EFI2 relay to supply 12v. So to fix up as factory you need to;

  • The fuse box EFI 1 relay Pin 5 needs to move to EFI 2 Pin 5 (This is the 12v wire to the fuel pump ecu)
  • The fuse box EFI 1 relay Pin 2 needs to bridge connections with EFI 2 Pin 2 (This is a shared ground)
  • The fuse box EFI 1 relay Pin 5 needs to bridge connections with EFI 2 Pin 1 (This is a shared 12v)

EFI 2 relay and fusing –

Early model TRAC fuses with 7.5amp, late model has an ETCS-i fuse with 15amp, so to fix up as factory you need to;

  • The fuse box EFI 2 pin1 goes to 12v (Shared 12v within fuse box for all fuses) – EFI2 30amp fuse
  • The fuse box EFI 2 relay Pin 3 needs to move to EFI 2 Fuse Pin 2 (This is the new EFI2 fuse)

Once all the EFI fuse box and relay wiring is complete you can send the black-red extra wire from the 5 pin engine loom connector to the current black-red 12v wire, the factory unit has a splice point.

ETCS-i 15amp fuse wiring under in fuse box is like the following;

Ensure the ETCS-i system has 12v+ fuse box and wiring. There are common issues when people swap engines from NA – TT and they forget to wire up the 12v+ wire to the ETCS-i system and put in a 15amp fuse.

  • The fuse box ETCS-i pin1 goes to the shared 12v (Shared 12v within fuse box for all fuses) – ETCS-i 15amp fuse
  • The fuse box ETCS-i pin2 goes to one of the plugs under the fuse box (BA2 5 pin connector which is the Blue-Red wire) engine loom connector – which then goes straight to the ECU (Block B78 (C) – Pin 7 +BM)

Further information on the ETCS-i system can be found on 2JZGarage here –

Body Loom wiring

I did spend some time comparing the body looms from both the NA and TT. See the body loom wiring diagrams link on page 1 for further details.

Foot well connectors on TT loom that won’t be hooked up at all;

BC1: Dark grey plug

  • BC1: 14-Orange is for EXO on ABS computer which goes to ABS on the ECU *This will be used if you have an advanced ECU
  • BC1:19-Blue/White is for exhaust temp sensor

BC2: White plug

  • All BC2 plugs: They are for Trac and Advanced ABS *This will be used if you have an advanced ECU

Foot well connectors that will be connected but missing wires;

BG1: Orange plug

  • BG1: 3-Black, Snow light
  • BG1: 16- Black/Yellow, PIM (Boost meter for late model)
  • BG1: 9- Yellow/Black, Slip/traction control off
  • BG1: 38- White, Slip/Traction control on (Will cut due to NA having wire there)
  • BG1: 33- Green, Oil level sensor

*Plugging in that are same thing but different colour: (the only different colour)

  • BG1: 15- Blue/Black, for check engine, is blue on NA

Depending on if you are replacing the whole fuse box or just custom wiring you will need to remove the 3x bolts in top of the fuse box. This is a spare fuse box I tracked down to use for wiring and fuses, I found having a spare was a better option then re-wiring the whole thing.“img_0991"


These are the connectors EA1 and EA3 that you will need to splice into from the fuse boxIMG_0011

Once you remove the fuse box it should look like this underneath“img_0014"

Once you have wired in the new connectors to the loom ensure you solder and wrap them“img_1115"

The connectors can be removed so you can run the new wires with more flexibility and test continuity easily, then solder and tape them all back together neatly“img_1121"

This is the stock engine loom and ECU I tracked down“img_1203"




Ensure you track down any other accessories such as Igniter, Air Flow Meter, MAP sensor, TPS sensor etc“img_0848"



One thing that threw me was 2x spare plugs, I found out this was for the advanced abs and traction control system that I won’t be using, and it gave me no warning lights for not connecting them“img_1178"

All the connectors plugged in, routed loom ready to connect ECU“img_1195"


The computer you can see in the background is the ABS ECU, this is the standard version, not the advanced version“img_1201"

o2 Sensor wires that needed to be extended from the aristo loom to supra connector“img_1208"



Water temp sender installed (Aristo engine doesn’t use one)“img_1212"



Make sure engine earths and oil pressure sensors are connected“img_1215"

One thought on “Toyota Supra NA-TT Conversion – Wiring – Part 3

  1. Awesome writeup.
    Not sure if it’s any help to anyone reading but I have a 98 2jz ge vvti ecu sitting around waiting for a good home. If anyone needs it I just put it up on ebay cheap.

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