R34 Gtt Rb26 Swap

[Arby's]

hey everyone just figured id post up my project thus far.

1999 R34 GTT RB25det Neo

when i got the car is had GTR items swapped for that gtr look on exterior. (hood, bumpersn side skirts) still looking to change out front fenders and do the over quarters to finish the body conversion.

I have also decided to do the RB26 swap. keep it RWD for this summer until i can locate proper front end parts to do the AWD swap (projected to under go that next winter)

i know this project is expensive and alot of people will say why not just buy a real GTR but being from the US an R34 GT-R is almost impossible to locate. there are only a few authentic R34 GT-Rs in the us. even the R34 GTT is pretty rare find. that being said lets not make this and arguement thread on GTT and GTRs.

I purchased an R32 RB26dett and AWD trans (both from R32 GT-R) i really wanted the R32 trans so i can make it selectable 2wd 4wd. the motor from the R32 and R33 also tends to be alot more affordable here in the states. and plus i plan to do full internal build next winter so i didnt see any benefits spending twice as much on the R34 GTR motor/trans. I also have an R33 RB25det and rwd trans sitting in shop that is for my 93 240sx but im going to put that on the back burner for a while and rob needed parts off that set up to make the R34 project move a bit more swiftly.

so in the shop we have an R34 GTT with RB25det Neo/Rwd trans, RB25det from R33 w/Rwd trans, RB26dett w/Awd trans from R32. all of which have full wire harnesses and ECUs (R33 motor also has greddy Emanage Ultimate computer with greddy harness kit to plug it in)

the plan:

RB26dett R32 motor, R33 RWD trans, use motor mounts from NEO to fit the RB26 in the R34.

Current status:

R34 Neo motor is ready to come out, RB26 in on engine stand (i freshened her up a bit and fitted a few goodies on it)

PROBLEM:

Wiring!!!!!!! the Harness for the Neo in the R34 is very complex, and also seems to have alot of "body control" features tied into it.

I have seen a few people do the RB26 swap in the R34s. what do they do for harness, ECU and keeping the creature comforts in the R34???? any and all help is needed!

[4dr32pwr]

Save yourself some mightmares and pay someone lol also You will need a rwd conversion sump if you do not want to run 4wd font as you will see front diff is one piece with sump.

[Arby's]

yep im using the R33 rb25 sump.

no one around here does that kinda work. i have seen the swap done and everyone said wiring wasnt fun till they figured it out. but no one posted what they did lol

[Arby's]

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.

cut wires on NEO harness to ECU.pdf

Other wires cut from R34 GTT harnesses.pdf

[Arby's]

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

pic 1 = plug 1
pic 2 = plug 2
pic 3 = harness 3
pic 4 = harness 4

[Arby's]

anyone have input?

[Arby's]

bump

[4dr32pwr]

Not sure if the 25 sump will go on a 26 mate pretty sure u need custom fab sump and just so you know when u get to it the 32 speedo is mechanically driven nd 34 is electronic so u will need to do the speedo cable modification you are better off just skipping the 33 box nd doing it properly so u dont need to fab a sump u dont need

[Arby's]

correct me if im wrong, but couldnt i just use the R33 trans and keep the gtr sump on the rb26 and just not hook anything up to it?

[Mitchee]

I have heavily dissected many R34 GTT harnesses across several cars and could probably wire one with my eyes closed. I have modded my Auto GTT harness to remove all the auto related wiring, removed traction control wiring, removed unneeded factory sensors and added in extra wiring for Oil pressure, fuel pressure and MAP sensor wiring, all while retaining ABS and it clips up to my RB26/30 as if it was stock. I run a Haltech R34 GTT plugin ECU.

I have spliced an R34 25GT (non turbo) harness with a GTT harness so it was a plug in job for my girlfriends R34 that we swapped a GTT motor into. The 25GT's have a separate ABS computer and harness which I had to move into the GTT harness while removing the existing GTT ABS/TCS wiring from it.

I have a pinout guide including a diagram of the large 'M53' or 'F3' plug (your 'plug 2') here: http://www.skylinesaustralia.com/forums/topic/420680-definitive-r34-gtt-wiring-pinouts/

Disregard wire color when tracing between plugs. Nissan used same coloring between devices so don't rely on this to be sure where a wire goes. There are splices and joins in wires inside harnesses also, so dont chop anything out because it may be supplying a signal to more than one other wire.

Your 'Plug 1' - ABS and traction control related. The red/green twisted wires is front left wheel speed. The grey 3 core is the electric TCS butterfly position sensor wiring (i think, going off memory here). You'll need to keep most signals going to this plug if you want to retain ABS etc.

Your 'Plug 2' - See my spreadsheet in the link above..

Your 'Harness 3' - ECCS and TCS relays. Brown is ECCS relay, this is an ECU controlled relay that powers everything up. It allows the ECU to shut everything down ifrequired. Blue is the throttle motor relay from memory.

Your 'Harness 4' - TCS Throttle control box. This takes signals from the ABS/TCS ECU in the boot via your 'Plug 1' and also the ECU.

My overall advice.. stay 2wd. Going 4wd later on will require a complete mechanical and electrical overhaul of the entire car. Chassis needs to be cut to allow for front driveshafts, you'll need to source an entire 34gtr front K frame, all of the atessa systems etc. Totally not worth it, just buy a 34GTR somehow.

Converting the car to run the rb26 as 2wd is much easier. You'll need to have the sump modified to remove the diff and possibly notched so it clears the front swaybar. Use the GTT engine mounts and it will bolt right in.

For electronics I would get a plug in fully programmable R34 GTT ECU, and run it with the stock GTT harness and sensors with the bits removed you don't need. This is exactly how I run my setup and it is flawless.