SW20 into ST165 last questions!

CodingParadox

New member
So, I've ordered a 1992 ST185 wiring harnes, which should be here in a week or so. I realize the wiring hell I'm going to have to go through to get this to work with my ST165 fusebox. A few questions:

1. I have a 93 JDM SW20 ECU. I believe the wiring harness plugs right into this, correct? Granted, we only have 92 fuel here instead of the 94 it's tuned for, but I can run it off this ECU until I find someone to trade me for a USDM one, right? (The harness will plug right in?)
2. Will I need any other parts from a 92/93 AT to make this harness work for me? I'm thinking mostly things that plug into the harness, like the relays, voltage regulators, etc. I have them all from the SW20, but I don't know if any of them plug into the ST185 harness. I'm only buying the harness, so I need to know what else I need for that.
3. The engine is an SW20 engine that I was gonna use for an FWD celica swap (before I bought the ST165.) I hence bought an SW20 pressure plate/clutch for it. The question is, now that I'm no longer mating the engine to an E153 (MR2T tranny,) will the clutch disc for SW20 accept the input shaft from the ST165 tranny? Boy can I not wait to have a new clutch. :)

I'm planning on using the 185 harness and rewiring the fusebox plugs to go into the 165 fusebox. Is there anything I should know ahead of time? I'm going to have to rewire the IC pump to work off accessory power, gonna have to rewire the like 5 fusebox plugs, etc. The general question is basically what parts am I gonna need to buy to make this work. This car's my daily driver, and while it barely works right now, it's still functional, and if I get half way through this swap and find out that I need to buy a part, that will suck immensely. :)

I'll document this project extensively for future swappers, I just really wanna make sure it's going to go smoothly ahead of time if possible.

Thanks! :D
 

ChrisD

New member
Have you read my write up? It explains most of the difficult stuff. http://www.gtfour.ca/howtoswap.html

You could use the 165 fuse box. I used the ST185 one because I didn't want to have to cut / solder all those really thick wires which I would have had to. They are mostly grounds and main power wires IIRC, and I didn't want to add any joints on them if I didn't need to.

Most MR2 stuff will plug right into the ST185 harness.

I don't think the clutch disc will work, but don't take my word on that.

Good luck!
 

CodingParadox

New member
Yah. Your writeup has all the hard stuff explained, and will be my savior on this. :D

I mostly just want to know about differences based on that I'm using an SW20 clip with JUST a ST185 harness instead of your route, which more conveniently had a full clip. I'd do the 185 fusebox route if I could as well, but unfortunately, all I have is an MR2T fusebox, which is just a nightmare jumble of wires, as is the MR2 wiring harness. It's kind of surprising really, the complete lack of any organization on the MR2T wiring harness. They're like well, we've got 40 wires that need to go places. Let's not use clips to organize any of it, we'll just screw them all down to random points on the fusebox and send em to random places in the harness. The stock wiring harness has what looks like are basically splices. It's like they had afterthoughts and needed extra copies of wires. *boggle*

The clutch disc is my main worry. I should probably ask toyota about that, though I suppose they probably can't help me. Maybe I'll call ACT and ask them...

I'm mostly trying to get all the stuff together ahead of time, because since I don't have the harness yet, I can't really verify answers to most of this stuff myself. I'm trying to plan ahead so that when the harness gets here I can start working, rather than starting to ask questions then, with 2 weeks of time lost. I'd like to hit the ground running as soon as the harness gets here. :)
 

nosboy

New member
i have an sw20 ecu on my 165 using a 185 harness. Believe me...its not plug and play...you will have to hack some wires, they are not exactly the same. Try to get the ecu pinout of a sw20 and a 185 and you will find out they are not exactly the same...though if you have the determination and ability you can do it yourself assuming you have average soldering and electrical experience.
 

CodingParadox

New member
Err... I was told that 92/93 SW20 ECU is same pinout as 92/93 ST185 ECU... Is that not true?... I mean, I can change pins of stuff as needed, I just didn't think I needed to.

Do you mean you have this on an ST165 engine or what? I'm going to be actually using a 2nd gen engine on this, so that should mostly be plug and play (I'd think...)
 
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