ST165 to ST185 ECU Conversion

gpmarzan

New member
DangerViking":3nszv6kb said:
Alright, almost done with a diagram for 165 <--> 185 harness conversion, and I'll be doing a writeup when it's all over, hopefully :)

On the 185, the circuit opening relay for the fuel pump is controlled by the FC line on the ECU, but looking on the 165 wiring diagram, the same plug on the circuit opening relay connected to the fuel pump is run by the AFM... therefore, if you use a 165 AFM, you don't need to connect the FC pin to anything? Just wanted to make sure, that's the only thing I really had any question left on.

Here's what I've got so far (the FC pin is circled so that I'll remember to look into it):

http://www.dangerviking.com/alltrac/ECUpinouts.JPG

P.S. this whole thread should probably be a sticky, since so many people are doing first to second gen swaps, and there's been some really good info on here

This is the last issue I have before I test the harness I made. Does anyone know if the FC wire goes to anything?

Also, where do you ground E22 on the st165 harness? is it connected to E1 ground wire?
 

gpmarzan

New member
looking back at both st165 and st185 ecu diagrams, E2 and E22 on the st165 ecu are both sensor grounds, and the st185 has only one sensor ground which is the E2. Do I just connect E2 and E22 together to the E2 of the st185 ecu?
 

gpmarzan

New member
Well, knowing E22 and E2 are both sensor grounds, I went ahead and connected both together with E2 of the st185 ecu.

The car did start. AF was in the high side topping my 16 A/F while engine is still cold. Double checked all the wires and they are all correct. I didnt wire up my intercooler pump so I didnt take it out for a test drive yet.
 

gpmarzan

New member
Had a chance to take it for a slow 2min slow drive. Idle seems to be rough at times. AF is still high around 16:1 both idle and partial throttle. I dont know, it did the same thing when I put back my st165 ecu but would go back to normal after a few minutes of driving. Maybe I just need to take it out for a spin around town. Ive triple checked every wire and they are all in the correct spots. I am still not sure where to ground the E22 wire and where the FC wire hooks up to if it does hook up to anything. Where are the guys that have done this?
 

gpmarzan

New member
After driving it around town, everything seems to level out. My air/fuel went back to normal and it seems to run smoother and a bit more responsive when you step on the gas. Its def worth the time to make one.
 

built2run

New member
i already have the conversion harness from 165 to 90-91 185 but i plan to add in an aem f-ic can you make something to add that in?
 

Dr Tweak

New member
Why don't you send along the patch harness you have and I'll wire in the FIC right into it. I carry the FIC as well so let me know if you want one :)

-Doc
 

gpmarzan

New member
small update

Ive driven the car one day to/from work regardless of idle AF being at 16:1. It ran fine till the light for the egr showed. Well, I wired up the THG pin EGR temp sensor wire according to the diagram shown here http://www.ts-ogn.no/files/3sgte-ecu-pinout.htm

The next day I drove the car, it stalled out on me 10min into driving and would not start back up. Good thing I was able to just hook the old ecu back. I checked every wire again tonight and everything looks to be in the right spots. I'll try to run the car again this weekend w/out the E22 wire hooked up which is the ground for the afm that doesnt have a match on the st185 ecu, and test a few more things. I dont know why my idle A/F is off. Makes me think there might be something wrong with the ecu I have.
 

aubeone

New member
I have completed the harness adapter that I have been working on, posted pics in my build thread, but here they are again for you...

IMG00142.jpg

IMG_0887.jpg


I also have available a copy of the Excel Workbook that I created during my completion of this project. If you want a copy, email me and I'll send it along.

I hope this is helpful.
 

siralys

New member
Ok so I have a 165 and want to run the 185 ecu. I know someone with an uncut jdm 185 harness and ecu, if I got the full 185 harness couln't I just put that in instead of getting an adapter harness?
 

aubeone

New member
Yes and no.

The plugs arent the same on the engine, so you would have to change them all over.

In your case I would just adapt the harness for the ecu.
 

xCH121Sx

New member
i got a hold of a trashed gen 2 harness from a friend. so i have the male plugs for the ecu.

i was thinking. everyones adapters are just in case their wiring was bad they can revert back to the 165ecu.

no ones had problems so far.

i was thinking since i dont have the female part of the ecu that i could solder new plugs directly to the 165 harness.

anyone see why i shouldnt do this?
 

aubeone

New member
In all honesty, after completing the adapter and mounting everything I ended up just swapping the plug ends anyway...I found the adapter took up way to much space in an narea where space is already a non-existent commodity.

Quick question also:

Has anyone come accross the situation in their swaps where there doesn't appear to be a match for the coldstart signal (STJ)??? Both the original 165 harness that I am using and the JDM 185 engine have cold start valves, but the ecu for the engine doesn't have an STJ signal/pin/wire....any ideas?
 

aubeone

New member
Noted, again...how would one wire the cold start injector then? Or do you just skip it all together?

I guess what I am looking for is guidance. What is the appropriate way to wire in the cold start on a jdm (185) engine with a usdm (165) harness?
 

Dr Tweak

New member
It's not really a big deal, the injector is turned on by the switch. On our harnesses I have the wire there in case a USDM ECU is being used, otherwise it isn't used at all.

-Doc
 

All4Traction

New member
Cool to see this thread is still alive.
Honestly, this was years ago and a lot of it is jibberish to me again. :(
Miss my car, hope this has helped a few people get their cars running good on the road :)
 
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