ok I have a 1999 R34 GTT. RB25det Neo motor. I have decided to do a GTR engine swap on it. the long term goal is AWD also but for this summer im going RB26dett Rwd. need to collect some more things to do the AWD conversion and summer is almost here.

What i have:
RB26dett and AWD trans from R32 GT-R (has harness and ECU)
in R34 is RB25det Neo with rwd manual trans (obviously has harness and ECU)
I also have a RB25det with rwd trans from R33 thats in my 240 but i am willing to rob parts off it for now to finish R34 project for summer (has harness and ECU)

the plan:
RB26dett from R32 GT-R, +Rwd trans from R33 Gtst.

big problem I am running into with this swap is the wiring and ECU. the R34 neo has alot of what i call "body control" stuff in the harness and ECU that i will loose when swapping engines.

i got the engine all ready to pull and when i pulled the harness from the ECU through the firewall that was when i realized i was about to loose a lot of features in my car (lights, AC, ABS and a whole lot more electrical). so now im freaking out. im worried the engine may work but ill have not functions in my car at best.

the first step was to attempt to separate the engine harness from the "body harness" this cant be done without cutting wires so i was very careful to log where each ware came from and where it was going while cutting. also got the Pinout diagram that tells colors or wires and functions.


I need help with this guys any and all input is great! i i have seen other members of this forum do RB26 swaps in GTTs but never saw what they did about wiring.

ok so i made a list of wires i cut to separate the body harness from engine harness

What i am calling the "body harness" is the harness that splits off at the fire wall right after it comes to engine bay, it immediately has plugs that hook up the the ABS system then the rest of the loom travels along the left inner fender then across the core/radiator support to fuse box. Im assuming that i need that part of harness to stay with the car.

the "engine harness" is what travels along fire wall to the motor.

i also self named some of the plugs or mini looms/harnesses that branch off 1-4. i will psot a pic of each mini harn or plug with a label to help make sense of this.
you will also notice some have mutiple choices, thats because i went by wire colors i didnt chase them back to the ECU yet to see exact pin. thats next so i can limit those down


Wire colors------------------Pin out ----- From -----To---- Function
Orange DblSilvrStrps-------4 ----Harness 3 --- ECU --- ECM & IGN coil relay control signal
Black/White----------------72 ----Harness 3 --- ECU --- control unit power
White/black----------------80 ----harness 3 --- ECU--- battery power supply
-------------------------------5 ---- harness 3--- ECU --- Tachometer drive signal
-------------------------------114 ---- harness 3 --- ECU--- Injector no. 4 cylinder drive signal
Black/White-----------------72 ---- Harness 3 --- ECU--- control unit power
White/green-----------------109 ---- Harness 3 --- ECU --- control unit pwr supply (counter
--------------------- electromotive feed back circuit)
thick grey wire made of 3 smaller wires… intel unknown at this point
Red/Black--------------------79 -- plug 1 ---- ECU --- ECM/TCM/TCS/ABS intergraded cntrl sgnl
White/black------------------80 -- plug 1 ---- ECU--- battery power supply
-------------------------------- 5 -- plug 1 ----ECU--- Tachometer drive signal
--------------------------------114 - plug 1 ----ECU --- Injector no. 4 cylinder drive signal
Green/orange----------------31 -- body harn. ----ECU --- ignition powr supply
---------------------------------78 -- body harn. ----ECU --- aux. electric fan relay control signal
Blue/yellow-------------------104 - body harn - ECU --- variable intake control solenoid vavle
White/black------------------80-- body harn -ECU --- battery power supply
--------------------------------5 -- body harn -ECU --- Tachometer drive signal
--------------------------------114 -body harn - ECU--- Injector no. 4 cylinder drive signal
Blue/black-------------------48 -- body harn- ECU --- pwr sup for TPS, refriferan pressure
----------------------------------------- Sensor, and turbo pressure sensor
Black--------------------------32 -- body harn- ECU--- control unit ground
Green/yellow DblSlvrStrps -66 -- body harn - ECU--- DB (databush 3 signal) rb25det a/t
Green/red DblSlvrStrps ---14 -- body harn- ECU --- AC control signal
Grey/red---------------------20 -- plug 2 ---- ECU --- Ignition switch (START) signal
--------------------------------120- plug 2 ---- ECU --- lockup solenoid valve control signal
Black SlvrStrps---------------25 -- plug 2 ---- ECU--- Control unit ground
Grey/blue DblSlvrStrps------17 -- plug 2 ---- ECU--- malfunction indicator lamp
Yellow/black DblSlvrStrps---22 -- plug 2 ---- ECU--- (CHK) check (Diagnosis start)
Orange------------------------111 - plug 2 ---- ECU--- Fuel pump terminal voltage
------------------------------------------ Control signal (rb25det)
Pink DblSlvrStrps------------21 -- plug 2---- ECU--- AC switch signal
Black/pink DblSlvrStrps----13-- plug2 ---- ECU --- fuel pump relay control signal
Brown/yellow----------------75 -- plug 2 ---- ECU --- (RX) receive (data input to control unit)
Red/blue---------------------9 --- plug 2 ---- ECU--- ign signal (power transistor) cyl #4
--------------------------------23 -- plug 2 ---- ECU--- throttle position sensor signal
Yellow/red DblSlvrStrps-----29 -- plug 2 ---- ECU--- vehicle speed sensor signal (sensor 2)
Pink/blue---------------------71-- plug 2 ---- ECU --- stop lamp switch signal
Green/orange----------------78-- plug 2 ---- ECU --- Aux electric fan relay contrl signal rb25
Black/white DblSlvrStrps----49 -- plug 2 ---- ECU --- rear defogger switch signal
White/black------------------80 -- plug 2 ---- ECU --- battery power supply
------------------------------- 5 --- plug 2 ---- ECU--- Tachometer drive signal
--------------------------------114 - plug 2 ---- ECU --- Injector no. 4 cylinder drive signal


Other wires cut from R34 GTT harnesses
Wire color---------------------------from ---------to
Black/green SlvrStrps---------------Body harn----Plug 3
Black/white--------------------------body harn----plug 3
White/black-------------------------body harn----plug 3
White/blue--------------------------plug 2-------engine harn
Brown--------------------------------plug 2-------engine harn
Red/white---------------------------plug 2-------harn 4
Brown/yellow DblSlvrStrps---------plug 2-------harn 4
Grey/red----------------------------plug 2-------harn 4
Green DblSlvrStrps-----------------plug 2-------harn 4
Green DblSlvrStrps-----------------plug 2-------harn 4
Green DblSlvrStrps-----------------plug 2-------harn 3
Yellow/red SlvrStrps---------------plug 2-------harn 3


here is the plugs and mini harnesses i marked as 1 2 3 or 4 in my break down on previous post attachments

no one?

Kind of in uncharted territory my friend, no one I know has a R34 GTT in the states lol. I have a NEO motor, but as far as the harness that came with the motor, it was only involved in the functions of running the engine, no "body" stuff. If you look in the FSM theres a wiring diagram that is really good for wiring, and will show you what you need to connect/cut. I would get that FSM first, if you cant find it, lemme know and I will send you a link for the download.

Best way to do wiring is get both wiring diagrams for the rb26 and 25 and basically merge them together on the actual harness. There wasnt a whole lot information out there when I did my swap into the s13 so thats what I ended up doing.

godzilla_753 wrote:Kind of in uncharted territory my friend, no one I know has a R34 GTT in the states lol. I have a NEO motor, but as far as the harness that came with the motor, it was only involved in the functions of running the engine, no "body" stuff. If you look in the FSM theres a wiring diagram that is really good for wiring, and will show you what you need to connect/cut. I would get that FSM first, if you cant find it, lemme know and I will send you a link for the download.

Best way to do wiring is get both wiring diagrams for the rb26 and 25 and basically merge them together on the actual harness. There wasnt a whole lot information out there when I did my swap into the s13 so thats what I ended up doing.

Yeah i know what you mean there are veryy little R34 GTT or GT-R in the US, but regardless of where they are located swap will be the same haha. I have done lots of motor swaps and conversions and never had a car with bodystuff tied into ECU before either. this car actually does tho. i listed some of the stuff in the previous posts a couple include (ABS controls, head lights, stop lamps, rear defog, tach controls...) I have put an RB in a 240, no problems, lots of honda conversions. even converted a Rev-up motor with 6 speed G35 Infinity to non rev up from 03 nissan Z. that took some ECU and wire harness research to make work... but this one is a real head scratcher

if you happen to have that link to the download that would help me out tremendously

Bump

Hey Mate
Iv just sorted out most of the issues that you will have as I just put an ls2 in my R34 the only thing I havnt got working yet is the ABS. Hence how I came across you posts searching for answers.
Have you made any progress since last post?
biggest issue is that if your car traction control by the looks it did because i recognise the connectors, is that the abs, traction ecu and engine ecu communicate to each other.

the harness that runs along the sil to the back is going to the ABS computer the computer that was up under the dash is for traction control, the blue and brown relays plugs are also for the traction control from what I found

i am currently emailing with a guy who has done the RB26 swap from and R33 gtr into is R34 GT-4. so neo motor but awd. ill post some updates in a sec

so basically what i am being told is to separate the harness going down the fender well which i did. now here is the steps i ahve done so far





so engine is now out and wires are separated as i listed in first posts.

here is the plugs i have left on NEO harness. not sure if all are supposed to stay with it or stay with car. currently trying to figure that out





here is plugs i have left on the "body harness"




and here is the R32 gtr harness and plugs and fuse panel i got

anyone feel free to drop some knowledge lol

Hey can you Email me @ [email protected]

I noticed that you said your using an RB25 transmission from an R33 GTS-T... just wanted to ask why you didnt use your R34 RB25 gearbox as they are stronger?

Thanks,
Glen

Ive done this exact swap a few times. I used the GTT harness and changed things as needed.