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Project SC : 2JZGTE ECU Wiring into SC300 Guide

To prep the SC for the GTE swap, I’ve sourced a MT GTE ECU and a Aristo ( JDM 2JZGTE ) engine harness. For those doing this swap into a SC300, the wiring is a lot easier than the typical S-Chassis wiring in that many of the vehicle’s functions and wires are the same.

Given the similarities between the SC300 and the MKIV Supra, this is really no surprise, however you will need to lengthen and extend the third plug or body plug as well as rewire.

This body plug disconnects from the sc300 along the firewall, next to the ABS module and near the windshield.

Upon splicing open this harness, you will notice many similarities with your Aristo harness.  The large connector on this harness connects to the SC300 body plug and also the small plug that leads to the ECU.

For ease of wiring installation, we are eliminating the following wires (Traction Control D17,  Pressure sender ( Dummy Light ) D10, and Transmission Shift indicator D1)

Use the following pinout and match the corresponding colors accordingly.

courtesy of clublexus.com. not my pic

The Aristo harness and ecu plugs :

For a pin by pin how to, refer to this chart here :

Now with your engine harness properly wired, you may now remove your old SC300 harness and install your GTE ECU and plug it in. Next up, we start yanking weight in preparation of motor swap, as well as installing a new Cometic head gasket, ARP head studs and selecting our turbo setup.

Happy boosting!

Case Studies : Project SRT-4 gets a heart transplant!

When we last left our Project SRT-4, it had an unfortunate head gasket tear and consequently had overheated. While the stock turbo had done it’s part putting down 355 @ 25 psi, it was definitely not happy at that level of boost.

While tearing the head off for service, we’ve decided to upgrade the turbo and exhaust manifold at the same time.

Helloooooooo...... Nurse!

We are installing a DNP Performance Tubular Manifold with External wastegate option, a Pro Street Stage V turbo with a 62-1 wheel and .70 cold side, and stage V hotside with .84 A/R.

Controlling the level of boost is a 44 mm Tial wastegate, and a BLOX manual boost controller, and of course a piggybacked SAFC on top of the Toys Stage II ecu upgrade with timing controls.

The only problem now is of course, fabricating a downpipe and 02 housing for the turbo so that it mates up to the full 3 inch catback exhaust on our SRT-4.

Parts used in this install

While the motor was out of the car, we fabbed up a test 02 housing and downpipe for this vehicle due to the exhaust facing towards the rear. Unfortunately, this test downpipe was misaligned, and upon bolting it all up we found it was exiting right onto the steering rack. Bad jujus.

Ouch....

Because of the engine layout and the choice in manifolds, the space to make this 3 inch downpipe clear is quite the challenge.

A look at the hotside and manifold setup in relation to the firewall.

A look at the clearance ( what little we have ) between the steering rack and the subframe in relation to the turbo and manifold.

A shot of the front side of the downpipe, and how close it is to the steering rack and the lines going into it.

Taking the downpipe off, we elect to gap out the top turn to push the flex section and flange away from the rack and towards the passenger side fender well.

After an hour of welding and cutting, we have successfully relocated the downpipe outlet to a more desirable location.

Next up, finishing up the job and welding the external dumptube to a tried and true location.