JDM wiring harness issues

OK, so I posted this issue on another site (you all know the one I'm talking about), and I'll copy and paste the start below, along with the link to that thread, but I can't seem to find any answers. Can anyone help me on this? Thanks.


OK, so I'm finishing up a '91 jdm tt SWAP into my 94 base, replacing the ECU and harness as well with their '91 JDM counterparts. I have a 1st gen radiator, so I'm set on that front, right? I'm expecting to have to rewire the OBD, but I have a few other questions. First, the O2 sensor. I know you have to rewire the front sensor on a USDM motor, but doesn't the JDM motor only have a rear? I have an AEM UEGO, which, from what I understand, can provide narrowband input to the ECU in place of the rear sensor, but what pin on a JDM ECU? In the engine bay, under the main junction box, the harness has a 10 pin plug, and the plug attached to the car has a 12 pin plug. The harness plug has 6 wires running into it, and the 12 pin has 7 wires. What is that clip for, and what should I do about the discrepancy in wire count? I think it's plug A-67, but I'm confused, as I don't understand the need for all those wires in that plug, if there is no front O2 sensor. Is there anything else I'm overlooking? Thanks.


http://www.3si.org/forum/f35/jdm-mot...7/#post6041323

1st gen GTO's only have one (1) O2 sensor thats located in the front pipe, thats it its all they have. there is nothing for O2 in the engine bay harness, its connected thru a hole below the ECU in the tunnel so that connector is inside the car.

I thought so. I read there is a way to use my AEM UEGO for narrowband instead of an O2 sensor? Also, are there any discrepancies between the wiring harnesses in first gen GTO's that would adversely affect my ability to 'plug and play' that harness into my 94??

only thing i can think of is the ecu! any piggyback/stand alone plug and play EMS should hook right in but dont take my word for that. you need to check pinouts between US and JDM versions of ECU's and year ranges.

I also have a JDM 91 ECU, so I should be good on that front. My only worry is upon a quick inspection of the plugs on the harness vs. those in the interior, there seems a be a remarkable lack of compatibility. Maybe I'll go double check those, to be sure. Also, did you have a chance to look at the link?? Any idea what any of those plugs are for in the pics?? And thanks.

Quote:

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Originally Posted by Hackurs

Here are pics of the various plugs that are in question, along with a brief description of their location. Thanks for the help.

http://i881.photobucket.com/albums/a...s/IMG_0330.jpg

This is the plug right beneath the junction box, next to the passenger side headlight. In my hand is the JDM harness, you can see the different number of pins.

http://i881.photobucket.com/albums/a...s/IMG_0331.jpg

These two are on the passenger side radiator, right next to the overflow bottle. The top is the body harness on my 94 Base, the bottom the plug from the 1G TT radiator.

http://i881.photobucket.com/albums/a...s/IMG_0332.jpg

Obviously right next to the wiper motor, on the JDM harness.

Can anyone explain what's up with these plugs in the pics?? Thanks.

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you didn't get the full harness i take it? ok see what i can do......

ok first pic i honestly cant place it. if i had a 1st gen i'd go tear it down and help better.... a buddy has one maybe i can get him to call round tomorrow? all i can say is.....do the wire colors match at all?

2nd pic obviously rad sensor harness...i think? they have the two temp senders in the bottom of the rad on 1st gens. match wires up to color match, if not again i can look at a buddies but honestly if the wire colors are different all you can do is run tests and connect accordingly.

last pic.... that last connecter should have a wire long enough to go under the wiper motor to around middle of the battery, that is for the coil resistor pack. i'm sure.

you really should have got the complete harness, it would have saved time and trouble.

sorry if this is all pointless but it looks like your going to have to do some testing and research.

good luck :)

Thanks for the help. It's definitely not pointless. The first pic, the wire colors don't match. I'll have to see if they do on the second pic. For the third pic.....the coil resistor pack is already plugged in..... ???? I have no idea what that plug is for.

OK, so after looking at the wires on the plugs in pic 2, it seems that one plug has 4 wires, and the other 6. The 4 wires DO match up colors to four of the wires on the 6 wire plug, but, obviously, it's short two wires. Then I noticed that the overflow bottle has a 2 wire plug, that connects to nothing..... and those 2 wires match up to the remaining two on the 6 wire plug. Is it coincidence, or did Mitsu split the 6 wire connector up in later years??

just had a thought...... the last pic.....looks like ecs plug. has it got one on the other side?

if you can get matching connecting plugs from a US wiring loom (maybe your old loom) you would be better to remove the plug from the ends and slide the ends of the JDM wires in there, the connectors have little clips that stick out locking the connectors into the plug. it will be neater than cutting and using inline connectors.

just a thought!
Attachment 1009

So, I can ignore it, since I don't have ECS, Aero, or any of that on my car. Thanks. I think my biggest worry is the second pic, since it's for the radiator. On the other side of the radiator, there were plugs, side by side. Correct me if I'm wrong, but isn't that the temp sensors?? Or am I mistaken, and those are the fan power sources? My thought on the first pic, is maybe the headlights??? Thanks again.

I would have thought that as well, but with an early GTO harness, early GTO radiator, and early ECU, it seemed to plug right up on the driver's side, but not the passenger (which is pic #2 on the previous page). Am I confused in the thought that the two driver's side plugs are the ones controlling the sensors, or are they the power for the fans? If the passenger's side plug (pic #2) is for the sensors, I can always splice, but I'm a little concerned about the difference in the number of wires. Am I right or wrong?

all you have to do is look at the wires from the plug to see where on the rad they go, rather than just splice wires, try to remove the connectors from the plug complete like i said, that way if you have a matching plug for either side you can use one of those to make the job neater.

if the car doesn't have ecs then dont worry about the ecs plugs.

Yeah, but what about the 4 wires vs the 6? That's the part I'm a little wary about.

use the 4 that match and see if you can math the remaining 2 to some other wires, if not tape them back.

ROFL. Sounds good to me

OK, so now that I've got it all together, it won't turn over. At all. Everything else is working. Fuel pump is working, lights, gauges, the works. The only other thing that isn't working are the head lights.