3rd Gen 3S-GE swapping information thread, Use your old harness w 2/3gen swaps? Options

[H8TRAIN]

Wiring for Non-Turbo 3SGE swaps into Celica ST204 is undocumented. Strange but true. As of today, we have two 6gc members (KAOS and mi645) attempting the 3rd gen 3sge swap with no information on how to wire them.

I understand that the swaps have been done and are not difficult. I’m starting this thread in hopes that those with the experience can answer some questions about these swaps. The details of the wiring all follow from one primary question.

Question: Is it best to use a 5sfe harness to swap in the 2/3gen 3sge?

(Reminder: 3sge means non turbo or na. Without a ‘t’ in it. Not 3sgte. Normally aspirated.This thread is about the 3sge, NOT the BEAMS. That is not a typo. Atmo. Strictly vacuum. Sucker not blower.)

Following are the threads and posts that lead to this question.

This was posted on here by 99gt3sge

you can use your 3s harness, i did a swap for my friend using a 3rd gen 3sge non beams with his original 5sfe harness, i had to wire up two injectors, re-pin the dizzy, and re-pin the ecu plugs to run the ge ecu. and extended some of the tb plugs and wire in the acis solenoid. it's not as easy as wiring a honda but it's very doable.

From eazy2001x on mr2oc:

thats a Gen 2 celica engine, your better off using a 5S harness and modding it to work.

From user pimpm3 on mr2oc:
Sadly, the image of the wiring changes that he made seems to be lost on the internet. I tried waybackmachine. No luck.

I had a hard time finding the exact instructions on how to wire in a 2nd Gen 3sge into a 1991 Na car, so I made a chart that shows how I did it. I hope this helps.

The 26 Pin and 16 Pin connectors plug straight into the ECU from the engine harness, the only wiring I had to do was on the 22 Pin connector. I took the wires from the 14 Pin Body harness conector that and soldered them on as follows to the 22 Pin connector so it will fit in the 3sge ecu. I labeled the wires on each conector before I cut them and then all you have to do is match them up.

The car starts right up and runs great. You can hook STA from the 22 Pin Connector up to the starter relay if you like but I did not and the car starts fine with out it.

Open questions for anyone who knows:

Can the 5sfe celica wiring harness be used on a 3rd gen 3sge swap?
If so what changes must be made?
Is it simply an act of opening both ecus, looking at the printed diagrams, and matching them up?

The 3rd gen motor is supposedly the easiest to install but is the 2nd gen really any harder? Can not the 5sfe harness be modified slightly to run the 2nd gen engine and ecu? Again do the ecus need to be simply opened to reveal the key to matching a few pins?

Any info and thoughts appreciated! There are people out there right now trying to find this information! I know I have been asking around for weeks now!

[Rusty]

Whats the spark like?

[KAOS]

Whats the spark like?

seems ok on startup, pulled each plug out during idle and the plugs are firing, but havent tested under load, which is when the backfiring happens...