Matt300ZXT

iTrader: (2)

I keep seeing all this stuff about how putting a 2JZ VVTI turbo from an Aristo is difficult because of the wiring. Yet I see early 1JZ Soarer swaps are directly plug and play, well essentially, after the harness is lengthened.

All the re-pinning of harnesses I read about, or buying a Dr Tweak harness, is that just so things inside the car will work? I mean, I'm just trying to figure this out; I'd assume you plug the harness from the motor into the ECU and theoretically the engine would run. However, tach wouldn't work, auxiliary gauges wouldn't work, a/c wouldn't kick on, etc.

Am I wrong in assuming that the harness included with the engine and the ECU will get the motor to run, however nothing in the car would mesh so to speak with the engine? Therefore necessitating the re-pinning so EVERYTHING works as if it were born that way.

LEXXIUM

iTrader: (1)

I think the plugs are different on aristo 2jzs, or ecu's had different plugs and that's when you need a complete wiring diagram of both vehicles to know which wire goes where when it comes to connecting ecu plugs to the speedo, ignition and all kinds of anti theft stuff
I'm not an expert but I read

It's not an easy task, that's why they're asking the money for it.

Ali SC3

iTrader: (10)

The engine harness goes from the ecu to the motor, and is designed to have everything on it to run the motor, however there are a handfull of wires that must be connected to the body harness for the motor/ecu to even turn on, and it connects to the body harness with plugs on the engine harness which are by the ecu. the engine harness plugs into the body harness to complete the circuit.

You are right in that the gauges would not work, but also the ecu would not get the signals it needs to turn the motor on and the main relays in the engine bay. It all sort of starts with the Key that is the IGN wire on the body plug, tells the ecu to turn on and that turns a circuit opening relay or something which kicks on the M-REL or Main relay (also on the body plug). once all this happens the ecu is ready to start and waiting from a start signal from the starter and once the ecu recieves that it starts a special startup procedure until it gets a fire off event (RPM's) and then it goes to its main startup map. If you ever see a JZ that is incredibly hard to start but seems to run well after its started, check the starter input signal to the ecu as it may not know its under startup but once the ignition is on the ecu will always try and run the motor ff the regular map if it is turning over from the starter even without the signal.

the body plugs do contain the things like the coolant temp, etc... and those won't work until you hook them up but its not like the engine will run without connecting at least the most important maybe 6 of the body plug wires. you could just figure out the basics needed and rewire those and figure out the others one at a time, you will probably get a ton of codes.

early 1jz non vvti came in soarers, and have the similar body plugs as SC's so thats why its just a simple extension.
all 2jzgte's came from a different chassis, so the body plugs are different and need to be changed to mate up to the sc300 body harness plugs, and if a JDM harness must be extended as well.
Newer ecu's which are vvti have a completely different ecu plug from non vvti as well as well as a different body plug than a SC.

If you are keeping the twins on a vvti it is worth it to use the GTE harness and do the lengthen and body plugs or get a new harness made. If you are going single turbo you can always use a GE harness which plugs into the body plugs already, and add the couple of things its missing from the GTE harness. most of the difference between a vvti GE harness and a vvti GTE harness besides the twin turbo vsv wires (not needed if going single turbo) is just 1 map sensor, which takes a whopping 3 wires to install.

This thread is how to install a non-vvt 2jzge into an older EFI celica/supra.
its not your motor combo exactly, but he outlines all the wires on the body plug you need to connect to start the ecu/motor.
Those handfull of inputs on the body plug is pretty universal to all toyota ecu's, and can be found on any EFI body plug harness, which is why its so easy to swap toyota motors and ecu's around if you can match up some wires from different diagrams.
the harness in this thread is from an GS/aristo and has the 1 large body plug. on the supra/SC its like 2-3 smaller body plugs different shape/size.
http://www.celicasupra.com/forums/sh...P-wiring-guide

Vrank

iTrader: (4)

Vvti gte aristo harness is nothing like the older aristo harness. Takes a lot to make it proper for an sc. Won't be hard to make it work but look like ****. What exactly are you after?

Vrank

iTrader: (4)

But to answer your basic question, a vvti gte aristo harness terminates to the ecu in the engine bay and also gets its power in the engine bay. The sc gets power inside the passenger kick panel. The plugs are also different. So you'd need to locate the appropriate plug that gives power to your stock engine, clip it off, and place it on the aristo harness, then lengthen it until it plugs in.

Bare minimum to run in your sc is
Power to injectors/ignition
+b circuit

Then at ecu:
Mrel
Batt
Igsw
+b

Early 1j you speak of that's simplest for the sc came out of a soarer, the rest have the same circuitry as the soarer, just in a different layout.

As for repinning, or buyin from a harness service vendor, its so that it works, and is proper. If you're not willing to do this proper, you're going to have problems, people will make fun of you at car meets, and half assing anything is not worth doing.

alucard655

I did this swap. Not sure what year your SC is but mine was a 2000. I also had Tweak build me a new harness. My tach works, my coolant temp works, my Speedometer works, and my A/C somehow works. I had some issues with the A/C initially but knock on wood, it works very well.

turbodremz

iTrader: (18)

After tackling an Aristo 2JZGTE VVT-i swap into an SC400, and doing the wiring in-house, I will tell you right now that even with all the good info posted above, its not that easy...especially if you want everything to work correctly such as your gauges.

From first hand experience, my suggestion is going to be spend the bit extra and order the Tweak harness. Im good with wiring and not afraid of it at all, but wiring the VVTi 2JZ from the Aristo is a PITA, and very time consuming. IF you want to handle the wiring yourself, and dont want too much of a headache, try and find the VVTi Supra harness, its slightly closer in wiring to the SC than the Aristo.

Ricklin

Meanwhile back to the mileage and range discussion. I've been guilty of drifting threads in the past, trying to stay on track, which for me is a challenge.
I really enjoy the range, 22+ gal. tank is unusual for a sedan, I drive a lot of highway, tomorrow will be a typical 300 mile day. A fuel tank that can outlast my bladder is impressive in itself, as I get older the tank gets smaller.
What is really impressive with my 05 is the mileage at much higher than legal speeds. On flat ground I see 22 MPG @ 105 MPH. Can do that speed far longer than a moment or two in rural OR, ID, and MT, WA will bust ya..... Yes, nowadays MT does have a speed limit. Be safe and sane and officer friendly will remain officer friendly. I typically fill @ around 525 or thereabouts. Good to know on the fuel pump, I am one who uses the full capacity.