Another swap wiring question...

[Crashsector]

Hello all... I have an interesting swap underway and I'm having a hell of a time finding some concrete wiring info. Here are the details:

Powertrain Donor:
1994 Legacy SS (EJ22T)
16G Turbo
Upgraded Injectors
JECS MAF
TurboXS DTEC for fuel, not sure about boost control at the moment
WRX 5MT and rear differential

Body Donor:
1991 Legacy L 5MT FWD

I have the engine/tranny/diff/subframe out of the powertrain donor and I'm in the process of trying to figure out what I'm in for wiring wise.

I found in one area on this site that the ECU pinout for all 90-94 Legacy's are the same, regardless of engine. However what I'm discovering now is that it seems that the harness connections inside the engine bay aren't the same, even though some of the connectors are.

Can anyone shed some light on the actual situation? Am I going to be able to plug-and-play with the turbo motor on one side and the turbo ecu on the other on the N/A harness? Or should I just bite the bullet and swap the entire turbo harness over?

Any help is appreciated...

--Andy

[Crashsector]

For the record, this is the powertrain donor

http://bbs.legacycentral.org/viewtopic. ... highlight=

[PhyrraM]

In your case, I think I would do a complete harness swap.

If your not willing to do that much labor/time you can add just the needed wires, but to do it right would involve basically the same labor as just chaging the harness (pulling the dash). The files are all here to be found. I would start with the stickies. I would use the engine harness from your current car and place it on your new engine if you choose this route as the connectors are differnt.

[Crashsector]

Yea I've been reading and absorbing everything pretty heavily. There's just a few things I can't completely wrap my head around.

They way I see it, I have two options. I'm also talking about two halves of the wiring harness: motor to engine bay, and engine bay to ECU.

Option 1: Take the motor to engine bay harness off the N/A motor and put it on the turbo motor.

Option 2: Take the engine bay to ECU harness out of the turbo car and put it in the N/A car.

Option 2 is probably "better", except for the fact that the powertrain car was rolled several times and I don't think it's going to be easy to get that harness out. I don't even know exactly where it runs or how to get it out. Option 1 would be my only route, but I really didn't want to have to pull the manifold or anything crazy on the donor motor.

Any input anyone?

Thanks!

--Andy

[PhyrraM]

There are 2 trunks of the harness that go into the engine bay.

One trunk goes from the driver's side footwell into the cavity just in front of the door, under the fender and fender-liner. It runs forward to just in front of the wheelwell where most of it branches into the engine compartment.

This is the big jumble that you see behind the battery. This is the leg that has the connectors that actually run to the motor itself.

The part that does not enter the engine bay runs forward and down to the radiator core support. It contains the lights and fans. It runs across the car to the passenger lights. It ends in that area.

The second main trunk exits the passenger compartment to the engine compartment behind the heater core. It branches both left and right along the upper firewall. It contains connectors for everything on the firewall and passenger inner-fenderwell. Engine-wise it contains, the O2 sensor, cam and crank sensors and the knock sensor. It then runs down the passenger fenderline and goes twords the MAF. It has the boost sensor and boost control solinoid.

The things you *need* to add are the boost sensor and boost control solinoid. The harness that contains both can only be accessed by removing the dash and heater core box. Once you do that to the wrecked car, I suppose you can add them back to your car without pulling the dash if you choose to route them differently. Of course this means adding your NA manifold harness to the turbo motor.

[Crashsector]

Well that harness you're talking about that runs along the front of the radiator core support is trashed, compliments of the accident. And the roof pillars are pushed down against the dash so it's going to be near impossible to get behind it.

I am ditching the boost control solenoid in favor of a MBC. I was told I can splice runs for the boost sensor and BCS to the ECU without using the harness, it's only a few wires.

With that being said, it seems like swapping the N/A manifold harness over onto the turbo motor would be a sight easier, yes?

Thanks for the help... it helps being able to bounce this stuff off someone.

--Andy

[PhyrraM]

Yes, you can splice the boost sensor into the current harness. I would also splice the boost control soliniod too. It's in the same place, so it won't really add any work to the job. Plus then it's there to test with and squash any codes that might pop up if it was absent.

There are a few wires relating to the crank and cam position sensors that must be relocated on the ecu plugs. They are reversed on turbo models. That I know is in a sticky. I think the ECU pinout thread in the electrical section.

It seems like your really adverse to the idea of pulling the dashes, so swapping the intake manifold harness will net you the best solution. You *might* be able to finagle the harness in without pulling the turbo manifold off the engine.

[Legacy777]

Just add the wiring for the boost related sensors, and switch the cam & crank positive leads at the ECU.

That should be all you have to do. Everything else should be fine since your donor car is MT.

[Crashsector]

Just add the wiring for the boost related sensors, and switch the cam & crank positive leads at the ECU.

That should be all you have to do. Everything else should be fine since your donor car is MT.

The information, as I have interpreted it, in the thread below leads me to believe this would be a really bad idea:

http://bbs.legacycentral.org/viewtopic.php?t=2215

This is why I'm really confused.

--Andy

[beatersubi]

To confuse you just a little more:
I just swapped a turbo motor into my n/a wagon. I used the stock harness on the turbo mani and added the extra wiring for the MAP sensor, press. exchange sol., and wastegate control sol.
Aside from a loose ground(my fault), that was causing me fits, all is well.

[Crashsector]

To confuse you just a little more:
I just swapped a turbo motor into my n/a wagon. I used the stock harness on the turbo mani and added the extra wiring for the MAP sensor, press. exchange sol., and wastegate control sol.
Aside from a loose ground(my fault), that was causing me fits, all is well.

What year was the turbo motor? I assume from your sig the N/A donor was a 92?

--Andy

[Legacy777]

I don't recall exactly which wire I tapped for 12v, but I haven't had any problems. I think you just need to be a little careful when picking the wire.


beatersubi, how did you use the turbo engine harness in your n/a car? The connector's behind the battery are different.

[beatersubi]

Sorry. Clarification: Stock n/a harness on turbo motor w/ extra wiring for sensors/ solenoids. I tapped into the IAC power for the extra stuff. So far, no problems.

Crashsector- Yeah, the donor car was a n/a 92 wagon L. I'm not sure what year the motor is, but I know it has the oil cooler/coolant warmer under the oil filter, and I think I read somewhere that it only came on one year turbo motor.

Everybody still suficiently confused?

[Crashsector]

Sorry. Clarification: Stock n/a harness on turbo motor w/ extra wiring for sensors/ solenoids. I tapped into the IAC power for the extra stuff. So far, no problems.

Crashsector- Yeah, the donor car was a n/a 92 wagon L. I'm not sure what year the motor is, but I know it has the oil cooler/coolant warmer under the oil filter, and I think I read somewhere that it only came on one year turbo motor.

Everybody still suficiently confused?

Yes, actually.

You say "Stock n/a harness on turbo motor...". Do you mean you removed the engine half of the harness from the N/A engine and put it on the turbo engine, and then plugged it in to the N/A body-side harness? Or do you mean you just plugged the turbo harness that was already on the turbo motor into the N/A harness in the N/A body?

--Andy

[Matt Monson]

Andy,
Let me try and clarify it for you. There are only two engine harnesses out there, or as we usually call them, intake manifold harnesses. There is actually no difference between a turbo and an NA intake manifold harness as far as pinouts are concerned.

Where the difference lies is in model years. 1990 and 1991 had one set of plugs (three of them, two for power and the 3rd is the "master" ground plug). The 92-94's used a slightly different set of plugs but with the exact same function and location. You obviously have to mate the intake manifold to whatever is coming out of the chassis by the battery. It doesn't matter if you got with the 2 square and one rectangle plug harness or the 1 square, 1 round, and one rectangle plug harness. You just have to make sure they match...

[Legacy777]

Yeah.....I used my old n/a intake manifold harness when I did my turbo swap since it matches the chassis wiring. I just moved the coolant temp sensors to the other side of the engine.

Also, here's a previous thread about the different plugs
http://bbs.legacycentral.org/viewtopic. ... 278#213278

[tahiti350]

Actually, the dash comes out in about 20 minutes, and the donor car would be easier yet as you can chop saw the winshield posts off at the cowl.
I pulled the entire harness from nose to the drivers seat out of the '90 sedan parts car in about 35 minutes (including dash removal, not including pulling fender and radiator).
How bad is the harness behind the fender?? unless it's severed you should be able to use it. Might just pull it, "just incase"....