st205 into st185 swap faq/ and parts compatibility

Q&A regarding engines, turbos, and intercoolers and power upgrades

Postby scothaniel » Fri Sep 30, 2005 8:15 pm

It takes a couple of hours to do, but its much simpler then changing the fuse box. I've done it enough times that it takes around 4 hours to completely convert the 185 harness to use on a 205 motor / ecu. 80% of the pins are the same - just take a look at :

http://alltrac.net/reference/ST185ECU.JPG
http://celicatech.net/forums/showthread.php?t=1526

Opening the conenctors and moving around the pins just takes a good eye and a fine pick.

You'll want to use the ST185 alternator and starter, otherwise you'll have to swap over the conenctors from the 205 harness - which isnt worth it.

Nearly all the sensor and vsv connectors are the same, and in the correct place (Throttle postion, idle, distributor, ignitor, etc...). The only 2 that need to be modified are for the air temp sensors:

- The ST205 has 2 air temp sensors - one it the intake manifold (THAM) and one in the air filter box (THA).
- The ST185 has an air temp sensor built into the AFM (THA) which will no longer be used.

So, you grab a standand 2-wire temp sensor (may have come with your 205 motor, if not hit the bone yard - just about every 94+ toyota has one), pull the THA and E2 wire out of the AFM and attach them to the sensor - extending the wires to where-ever you want to put the sensor. Mine just zip-tied to a bumper support. Done.

The second air temp sensor is in the intake manifold to the right of the TB. Its 2 wires as well. If your ST185 had an EGR, use those wires - cut off the EGR sensor plug and solder on the 205's air temp plug. The EGR wire is now the THAM wire. Done.

Like I said before, you'll either need an extra sensor for the water elbow or you'll need to ditch something. The 205 has 2 water temp sensors / switches and the 185 has 4. One is for the cold-start injector, which doesn't exist on the 205 and therefore not needed. The others are the A/C temp switch, water temp gauge, water temp sensor (ecu). You could easily bypass the A/C temp switch by grounding the wire, just dont turn the A/C on if the car is overheating!

Wow, didnt mean to write a manual here... sorry.
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Postby CMS-GT4 » Fri Sep 30, 2005 8:34 pm

Thanks for all your info. Could I save myself some time and work by using the main engine harness for the 205, and just using the 185 fuse/body box harness? That is the only part cut really.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby k_trac » Fri Sep 30, 2005 10:24 pm

SOOOOO.......

Scothaniel, you are saying that you just use the WHOLE 185 harness to plug into the 205 motor with some sensor modifications and pin modifications for the 205 ecu?

I do see advantages to that, being that you dont have to lengthen the 205 harness....even though I am already 80% done...AHHHHH! Looks kinda like shiiiat!

I think LechacZ did his differently than that.....I think he kept the 205 harness on the engine, lengthened it, and mated it into the 185 fuse box....and thats what I was in the long, procrastinating process doing......

Seriously, Scothaniel, if I could call you on the phone and have you just explain this in real time, real words...I would be eternally grateful! we can conference call with CMS-GT4!

If you could PM me your # that would kick ass. Have an import event happening this coming sat....would be awsome if the car ran by then....

Thanks,
Keith
The Screamer - '90 Red Alltrac - ST205 swap, 3" MP, 3" catback, intake, spec III clutch - FOR SALE $7000
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Postby TheStig » Fri Sep 30, 2005 11:32 pm

this is weird .. I know people that have done the 205 swap into the 185 in a night or two. Cant remember them having to struggel with the wiring etc. Think they just janked out everything from the 185 enginebay and used it all from the 205 frontclip....
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Postby CMS-GT4 » Fri Sep 30, 2005 11:55 pm

I am up for whatever calls I need to make.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby CMS-GT4 » Sun Oct 02, 2005 5:09 pm

Slight change of plans, I wll be using my RC box. Can't get to my '92 box, and I need this car on the road. I am planning a gearbox upgrade/clutch flywheel etc... down the road anyway. Won't kill me to use a higher FD for 7 months or so. I am heading to get the car now. Hope to have it running by the end of the week.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby InitialD93 » Sun Oct 02, 2005 5:18 pm

u better have it running in time for the meet josh... i might actually be able to keep up this year... holy shit ive done alot to my car since the last meet.. i just realized that
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Postby CMS-GT4 » Sun Oct 02, 2005 11:28 pm

I hope to have 245's on some 17x9's by the meet. Plus in the range of 270-290hp. So we will see. :evil:
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby CMS-GT4 » Mon Oct 03, 2005 12:19 am

Whats your progress K_trac? I should be giving you a call tomorrow to see what you have sorted out.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby CMS-GT4 » Mon Oct 03, 2005 5:37 pm

scothaniel wrote: I have posted a little drawing for which pins to change on the ST185 harness.



Where is this drawing posted? It would be a great reference.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby scothaniel » Mon Oct 03, 2005 6:03 pm

Sorry for not responding earlier - had a few issues this weekend that kept me busy. I'll PM my phone number, glad to help where ever I can.

The first time I did the swap, I used the 205 harness and tried to swap the 205 fuse box over - big mistake. The bulk of the issues were because I dont have the BGB for the 205, so I dont have all the diagrams for the secondary systems. I spent a lot of hours repinning the dash plugs and working through the fuse box, checking for proper connectivity. It was a mess. I ended up ditching the harness, then later on swapped over just the 205 fuse box in an attempt to free up 2" of space. I need a bigger engine bay!

The second time I used all 185 harnesses only, and re-pinned the 3 connectors for the 205 ECU, then went through the diagrams to make sure all the sensors were getting the proper voltage. Made the changes I listed before and it worked perfectly. So much easier. I made a little diagram that others have used for repinning thiers.

My last 3 harness projects have been more difficult, and have really taught me some valueable lessons - like keeping the wiring as simple as possible. For instance, I spent all weekend troubleshooting some weird s#&% on one harness without any luck. The engine is a 3rd gen 3SGE converted to turbo, the ECU is from a ST205, the harness is from the 3SGE (had to be lengthened and modified) and the car is a 97 Celica ST. I have a major issue with the ECU / ISC valve and troubleshooting has been an absolute nightmare since none of it is stock. A full weeked and the car is no closer to being on the road... very depressing.

When you leave the internals of the harness in tact, its one less thing to worry about, one more thing to rule out when there is a problem.

Just my 2 cents.
Last edited by scothaniel on Mon Oct 03, 2005 6:08 pm, edited 1 time in total.
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Postby scothaniel » Mon Oct 03, 2005 6:06 pm

Oh - and if you guys have a spare 185 engine harness sitting around, let me know. I need to replace the harness in my car since I've butchered it installing a Link Plus EMS ( harness project #3).
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Postby CMS-GT4 » Mon Oct 03, 2005 6:18 pm

Yes, I agree. Simple as possible. If it would be easier using the entire 185 harness, and just repinning it, I am up for that. PM me your number when you get the chance. I will be working long days till wednesday, and plan on starting on this wednesday or thursday.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby CMS-GT4 » Fri Oct 07, 2005 1:29 am

Scott,

Can you email your number to:
iliketoplay@homail.com

The PM system is down.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby CMS-GT4 » Mon Oct 10, 2005 1:07 pm

Where did everone go? :shrug:
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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