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Engine Harness Plugs - Need help sorting wiring differences between model year changes.

I've got a 1991 Legacy SS sedan that I swapped a 1994 Legacy Turbo Wagon engine into. My problem at hand is the difference of the engine plugs between the MY90-92 and the MY93-94. I didn't know about the differences until I got the newer engine in there.

In this picture I show the (1991) chassis side harness 2 square and one rectangle, coming out under neath the engine bay fuse box (in my hand). Also in the photo is the (1994) engine plugs which are 1 square, 1 rectangle and 1 round (zip-tied to the intake).



I don't have the 91 engine harness, but I've got the whole 94 donor car, so I could swap that chassis harness into the 91. I need to learn more about that. And find out if it will match up and plug in the same on the other end and where that is. Does it plug into the ECU or fuse panel or what. That's my dilemma.

If you want to see more of this build so far, I have some documentation on my local forum at this link.
http://www.fairbanksforum.com/phpbb3/vi ... =11&t=7056

So, if anyone can give me suggestions, or threads that deal with this topic or are related, please let me know.

Thanks for your time,
-Dominic

I think the easiest route would be to obtain a '91 engine harness.

I don't think pulling the dash to swap a chassis harness is worth the effort.

The round connector on the '92+ is all grounds, I do not know if the retangular pair on the '91 is the same.

If the other two connectors will physically plug in, it should be possible to re-pin the engine side to match the '91 wiring pinouts.

I seem to remember something about the '90/'91 Hitachi based cars having a compatable engine harness, but don't quote me on that until examining the diagrams.

PhyrraM, thank you for your input. Do you have a resource for these diagrams? for a 91 and a 94? I am not opposed to reading and researching this too. Any other threads to note would be cool too.

In the mean time, I will try to get my hands on an older style turbo engine harness.

Personally I feel like I am running out of time. It's only getting colder here in Fairbanks. The cars and all my tools are sitting at my girlfriends dad's house. And to work on it, I need to ask him to park outside. It's been fine so far, but I don't want to overextend my welcome to the garage. So I wanted to post this to get insight from the collective knowledge.

All the 90 & 91's (non turbo & turbo) all had the three square plugs. As mentioned 92 onward for the turbos the third plug was round. The 92 and newer non-turbo just had two plugs. What you can do is get a 90-91 non-turbo engine harness and move the coolant temp sensors wires to the driver's side of the motor to match the turbo motor. That is what I did with my 90 non-turbo engine harness when I did my turbo swap. That is going to be the easiest and cheapest option for you.

Legacy777 wrote:All the 90 & 91's (non turbo & turbo) all had the three square plugs. As mentioned 92 onward for the turbos the third plug was round. The 92 and newer non-turbo just had two plugs. What you can do is get a 90-91 non-turbo engine harness and move the coolant temp sensors wires to the driver's side of the motor to match the turbo motor. That is what I did with my 90 non-turbo engine harness when I did my turbo swap. That is going to be the easiest and cheapest option for you.

Are the wiring pin-outs the same for the plugs? <-- I still have no way of checking this out. Any links to diagrams?

It would be easy to find the older style harnesses (non-turbo) in the junkyards around here.

Are the wiring pin-outs the same for what plugs?

If the plug on the engine harness fits into the plug on the chassis harness, the pin outs should be the same. if you're asking whether the 91 turbo engine harness should be the same as the 90-91 non-turbo engine harness, the answer should be yes they're the same.

Right on. Thanks for the info. I will be going to the junkyard next week to pick up some wiring harnesses and parts.

I am still searching for some wiring diagrams that show what the pin-outs for the harness plugs are. I would like to make sure I get them wired up correctly. I'd really like to get diagrams for the earlier and later versions so I can compare them.

I will keep looking. If you have any resources, let me know.

http://www.main.experiencetherave.com/s ... agrams.zip

http://www.main.experiencetherave.com/s ... and_Elect/

Well I searched one junk yard and all the Legacy's were missing there engines. That was a bummer. That was a few weeks ago.

I stopped by the parts dept at my local Subaru dealership. The guy there has been really cool to me. I go in and BS with him once in a while. Anyway I asked him if he could order the harness for me, (I found the part number) but it's not available anymore. On the up side though, I asked if he had access to the wiring diagrams for the two different years, he got the service manuals from the technicians and made photo copies of all the engine wiring pages for me.

Today I went to a Subaru graveyard parts yard behind a shop a buddy of mine works at, and scored the intake with harness with the 3 square plugs off an older N/A Legacy. Now I gotta get the car in the garage again and swap that harness now. It is pretty cold today too. It was -15 when I was out there pulling parts. Maybe next weekend I'll have time to get to it.

Yeah that's a little cold to be out pulling parts

No kidding, but I'm glad I got it when I did. It dropped to -30 that night. Friday is forecasted to be warmer. I might go out the that yard again and look for some more stuff. Maybe some 92-94 N/A Fuel rails for my Yellow STi injectors.